Crosslinked Compositions, Method of Making Them, and Articles Comprising Them

ABSTRACT

The present invention relates to a composition comprising at least one propylene-based polymer comprising less than 0.1 wt. % diene-derived units based on the weight of the propylene-based polymer, an antioxidant, and a co-agent. The composition can be at least partially crosslinked by electron beam irradiation in a dose of less than 200 kGy, and may be further formed into articles including fibers, yarns, films, and nonwovens, among others. The propylene-based polymer of the present invention may be a polymer blend formed by forming a reactor blend from of two or more polymers produced in two or more reactors.

PRIORITY CLAIM

This application is a continuation-in-part of International ApplicationPCT/US2010/050243 (bearing Attorney Docket No. 2009EM213), filed Sep.24, 2010, which claims the benefit of U.S. Provisional PatentApplication No. 61/248,190, filed Oct. 2, 2009, the disclosure of all ofwhich are incorporated herein by reference in their entirety.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. application Ser. No. 13/273,323(bearing Attorney Docket No. 2011EM251), filed Oct. 14, 2011, and U.S.application Ser. No. 12/130,745 (bearing Attorney Docket No. 2008EM146),filed May 30, 2008, now U.S. Pat. No. 7,867,433, the disclosures ofwhich are incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a crosslinkable composition and acrosslinked composition, in particular to a composition comprisingpropylene-based polymer that substantially lacks diene-derived units,and to a method for making the same.

BACKGROUND OF THE INVENTION

Polyolefin polymers and polymer blends are known for their versatilityand applicability in a wide variety of uses. In particular, manypolyolefin polymers, including copolymers of propylene with otherα-olefins such as ethylene, are well suited for use in applicationsrequiring good stretchability, elasticity, and strength. Materials withgood stretchability and elasticity are used to manufacture a variety ofdisposable articles in addition to durable articles including but notlimited to incontinence pads, disposable diapers, training pants,clothing, undergarments, sports apparel, automotive trim,weather-stripping, gaskets, and furniture upholstery. For clothing,stretchability and elasticity are performance attributes that allow thematerials to provide a closely conforming fit to the body of the wearer.

While numerous materials are known to exhibit excellent stress-strainproperties and elasticity at room temperatures, it is often desirablefor elastic materials to provide a conforming or secure fit duringrepeated use, during extensions and retractions at elevated or depressedtemperatures, or in automobile interiors during summer months.Elasticity at elevated temperatures is also important for maintainingtight tolerances throughout temperature cycles. In particular, elasticmaterials used for repeated wear clothing or garments are preferred tomaintain their integrity and elastic performance after laundering.

Spandex, a segmented polyurethane urea elastic material, is currentlyused in various durable fabrics. For example, fibers made from Spandexhave been used in launderable apparels, fabrics, durable and disposablefurnishing, beddings, etc. Similar to conventional uncrosslinkedpolyolefin-based elastic materials, articles made from Spandex can loseintegrity, shape, and elastic properties when subjected to elevatedtemperatures. Thus, Spandex is not suitable for many co-knittingapplications with high temperature fibers, such as polyester fibers.

Propylene-based polymers having good elastic properties are known andhave been used for stretchable clothing. See, for example, U.S. Pat. No.6,525,157 and U.S. Pat. No. 6,342,565. U.S. Pat. No. 6,342,565, inparticular, discloses a soft, set-resistant, annealed fiber comprising ablend of polyolefins. The blend has a flexural modulus less than orequal to 12,000 psi and includes from 75 to 98 wt. % of a first polymercomponent and is from 2 to 25 wt. % of a second polymer component. Thefirst polymer component is a propylene-ethylene polymer having at least80 wt. % propylene and up to 20 wt. % ethylene, a melting point (Tm) byDSC in the range of from 25 to 70° C., and a heat of fusion less than 25J/g. The second polymer component is a stereoregular isotacticpolypropylene having a melting point by DSC of greater than 130° C., anda heat of fusion greater than 120 J/g. The fiber exhibits a resistanceto set equal to or less than 80% from a 400% tensile deformation. Thepolyolefin blend is said to be substantially non-crosslinked.

U.S. Pat. No. 6,500,563 discloses blends of two different types ofpolypropylene, including blends made from a polypropylene having a Tm ofless than 110° C. and propylene-ethylene copolymer that hasisotactically arranged propylene derived sequences and Tm less than 105°C.

U.S. Publication No. 2006/0183861 discloses blends of at least twopolymers incorporating propylene-derived units and process for producingsuch blends. The first polymer of the blend is a low crystallinitypolymer including propylene-derived units. The second polymer is a highcrystallinity polymer including propylene-derived units. The polymerblends exhibit the beneficial performance characteristics of lowcrystallinity propylene polymers while minimizing certain processing andhandling problems associated with low crystallinity propylene polymers.

U.S. Publication No. 2005/0107534 A1 discloses curable and curedcomposition comprising a propylene-based elastomer optionally includinga diene, and having isotactic polypropylene crystallinity, a meltingpoint by DSC equal to or less than 110° C., and a heat of fusion of from5 J/g to 50 J/g. The disclosure includes a blend composition comprisingany of the propylene-based elastomers. The disclosure also includescompositions comprising any of the propylene-based elastomers and 1 to100 parts by weight of inorganic filler per 100 parts of polymer.

Three component blends of isotactic polypropylene impact modifyingamounts of an ethylene-propylene based rubber or low density ethylenecopolymer and a propylene-based elastomer as compatibilizer aredescribed in EP 0946640, EP 0946641, EP 0969043 and EP 1098934.

International publication No. WO 04/014988 describes blends of isotacticpolypropylene with non-functionalized plasticizers such aspoly-alpha-olefins. International Publication No. WO 03/040233 alsodiscloses two component blends with the isotactic is polypropylene asthe predominant, matrix phase and the propylene-based copolymer servingas an impact modifier.

EP 1003814 and U.S. Pat. No. 6,642,316 disclose two-component blends ofsmall amounts of isotactic polypropylene and predominant amounts of anethylene based elastomer. EP 0374695 discloses visually homogeneous twocomponent blends, however, using 40 wt. % or less of the propylene-basedcopolymer. WO 00/69963 describes films made of two-component blends withfrom 75 to 98 wt. % of a propylene ethylene based elastomer having aheat of fusion of less than 25 J/g.

Other related references include International Publication No. WO2006/102419, U.S. Publication Nos.: 2005/0107529; 2005/0107530;2005/0131142; and 2005/0107534.

SUMMARY OF THE INVENTION

The present invention is directed to a composition comprising one ormore propylene-based polymers substantially lacking diene-derived units,one or more antioxidants, and one or more co-agents, and to a method formaking such a composition. In some embodiments, the one or morepropylene-based polymers may be a polymer blend formed by forming areactor blend of two or more polymers produced in two or more reactors.The present invention also provides a crosslinked composition. In someembodiments, the crosslinked composition can be prepared by exposure toelectron beams, and may be further formed into articles includingfibers, films, and nonwovens, among others. The compositions describedherein are expected to exhibit improved mechanical and elasticproperties and pellet stability when compared to similar materials knownin the art. These compositions are useful preparing fibers for apparels,diaper yarns elastic stretch engine for hygiene and Femcareapplications, films with the stretch performance for apparel elasticbands, high performance film of elastic laminate structures for thehygiene business and the like.

In one aspect, the invention provides a method for making a crosslinkedcomposition comprising the step of crosslinking the composition usingelectron beam radiation having an electron beam dose of about 200 kGy orless, the composition comprising:

-   -   i) a propylene-based polymer comprising from about 75 wt. % to        about 99 wt. % propylene-derived units, from about 1 wt. % to        about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.1 wt. % diene-derived units, based on the weight        of the propylene-based polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate; and    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine.

In some embodiments, the propylene-based polymer is a polymer blendformed by forming a reactor blend of a first polymer formed in a firstreactor and a second polymer formed in a second reactor, the firstpolymer comprising from about 75 to about 99 wt. % propylene-derivedunits, from about 1 to about 25 wt. % ethylene and/or C₄-C₂₀α-olefin-derived units, and less than 0.1 wt. % diene-derived units,based on the weight of the first polymer; and the second polymercomprising from about 75 to about 99 wt. % propylene-derived units, fromabout 1 to about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,and less than 0.1 wt. % diene-derived units, based on the weight of thesecond polymer.

In another aspect, the invention provides a composition comprising:

-   -   i) a polymer blend formed by forming a reactor blend of a first        polymer formed in a first reactor and a second polymer formed in        a second reactor, the first polymer comprising from about 75 wt.        % to about 99 wt. % propylene-derived units, from about 1 wt. %        to about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.05 wt. % diene-derived units based on the weight        of the first polymer; and the second polymer comprising from        about 75 wt. % to about 99 wt. % propylene-derived units, from        about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀        α-olefin-derived units, and less than 0.05 wt. % diene-derived        units based on the weight of the second polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate; and    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine.

In another aspect, the invention provides a crosslinked composition,comprising:

-   -   i) a propylene-based polymer comprising from about 75 wt. % to        about 99 wt. % propylene-derived units, from about 1 wt. % to        about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.1 wt. % diene-derived units, based on the weight        of the propylene-based polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate; and    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine; and    -   iv) a polyolefinic thermoplastic resin; and

wherein the crosslinked composition has greater than 40% xyleneinsolubles as measured according to ASTM-D 5492.

In some embodiments of the above aspects, the propylene-based elastomersubstantially lacks diene-derived units.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 and 2 depict the improvement of Tension Set at 70° C. of theinventive crosslinked compositions.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a composition comprising one ormore propylene-based polymers substantially lacking of diene-derivedunits, one or more co-agents, and one or more antioxidants and acrosslinked composition. In some embodiments of the invention, thepropylene-based polymer can be polymer blends of a first propylene-basedpolymer formed in a first reactor with a second propylene-based polymerproduced in a second reactor. These polymer blends may be compoundedwith a variety of additional components including coagents,antioxidants, secondary elastomers, polypropylene, additives, fillers,and additive oils, among others. In some embodiments, crosslinking ofthe propylene-based polymer, including the polymer blends, isaccomplished via electron beam radiation. In particular, whenpropylene-based polymer, including the polymer blends described herein,are compounded with a coagent, an antioxidant, and/or UV sensitizer andsubsequently crosslinked, they are expected to have improved propertiessuch as peak stress, peak elongation, and tension set when compared tocrosslinked polymer blends prepared in the same manner and havingsimilar compositions but substantially lacking the coagent, antioxidant,and/or UV stabilizer. The compositions and methods for their productionare described in greater detail below.

Propylene-Based Polymer

The propylene-based polymer can be one or more propylene-α-olefincopolymers. The terms “propylene-based polymer” as used herein willrefer to propylene-α-olefin copolymers. The propylene-based polymer ofthe invention comprises less than 0.1 wt. % based on the weight ofpropylene-based polymer. For simplicity the term “substantiallylack(ing)” as used herein refers to that the amount of the diene-derivedunits is less than 0.1 is wt. % based on the total weight of thepropylene-based polymer, preferably less than 0.05 wt. %, morepreferably less than 0.01 wt. %, and most preferably equal to 0 wt. %.

As used herein, the term “copolymer” is intended to mean a materialwhich is prepared by copolymerizing at least two different co-monomertypes, including co-monomers derived from ethylene or higher α-olefins,such as C₄-C₂₀ α-olefins. One or more other different co-monomer typesmay also be included in the copolymer such that the copolymer definitionincludes terpolymers as well as copolymers comprising four or moredifferent comonomer types. The term “monomer” or “comonomer” as usedherein can refer to the monomer used to form the polymer, i.e., theunreacted chemical compound in the form prior to polymerization, and canalso refer to the monomer after it has been incorporated into thepolymer, also referred to herein as a “[monomer]-derived unit”, which byvirtue of the polymerization reaction typically has fewer hydrogen atomsthan it does prior to the polymerization reaction. Different monomersare discussed herein, including propylene monomers, and ethylenemonomers.

In some embodiments, the propylene-based polymer can be prepared bypolymerizing propylene with ethylene, or at least one C₄-C₂₀ α-olefin,or a combination of ethylene and at least one C₄-C₂₀ α-olefin. Preferredmethods and catalysts for producing the propylene-based polymers arefound in U.S. Publication Nos. 2004/0236042, WO 05/049672, and U.S. Pat.No. 6,881,800, all of which are incorporated herein by reference.Pyridine amine complexes, such as those described in WO03/040201 arealso useful to produce the propylene-based polymers useful herein. Thecatalyst can involve a fluxional complex, which undergoes periodicintra-molecular re-arrangement so as to provide the desired interruptionof stereoregularity as in U.S. Pat. No. 6,559,262. The catalyst can be astereorigid complex with mixed influence on propylene insertion, seeRieger EP 1070087. The catalyst described in EP 1614699 could also beused for the production of backbones suitable for the invention. In oneor more embodiments, the propylene-based polymer can comprise a blend ofdiscrete random propylene-based polymers. Such blends can includeethylene-based polymers and propylene-based polymers, or at least one ofeach such ethylene-based polymers and propylene-based polymers. Thenumber of propylene-based polymers can be three or less, more preferablytwo or less.

The propylene-based polymer can have an average propylene (orpropylene-derived units) content on a weight percent basis of from about60 wt. % to about 99.7 wt. %, more preferably from about 65 wt. % toabout 99.5 wt. %, more preferably from about 75 is wt. % to about 99 wt.%, more preferably from about 75 wt. % to about 95 wt. % based on theweight of the propylene-based polymer. In one embodiment, the balancecomprises diene. In another embodiment, the balance comprises one ormore dienes and one or more of the α-olefins described previously. Otherpreferred ranges are from about 80 wt. % to about 95 wt. % propylene,more preferably from about 83 wt. % to about 95 wt. % propylene, morepreferably from about 84 wt. % to about 95 wt. % propylene, and morepreferably from about 84 wt. % to about 94 wt. % propylene based on theweight of the propylene-based polymer. The balance of thepropylene-based polymer comprises one or more alpha-olefins. In one ormore embodiments above or elsewhere herein, the alpha-olefin isethylene, butene, hexene or octene. In other embodiments, twoalpha-olefins are present, preferably ethylene and one of butene, hexeneor octene.

Preferably, the propylene-based polymer of the present inventionsubstantially lacks diene-derived units. That is, the propylene-basedpolymer comprises less than 0.1 wt. % of diene-derived units based onthe weight of the propylene-based polymer, more preferably less than0.05 wt. %, more preferably about 0.03 wt. %, even more preferably about0.01 wt. %, and most preferably 0 wt. %. The term “diene” as used hereinis defined as a hydrocarbon compound that has two unsaturation sites,i.e., a compound having two double bonds connecting carbon atoms.Exemplary dienes suitable for use in the present invention include, butare not limited to, butadiene, pentadiene, hexadiene (e.g.,1,4-hexadiene), heptadiene (e.g., 1,6-heptadiene), octadiene (e.g.,1,7-octadiene), nonadiene (e.g., 1,8-nonadiene), decadiene (e.g.,1,9-decadiene), undecadiene (e.g., 1,10-undecadiene), dodecadiene (e.g.,1,11-dodecadiene), tridecadiene (e.g., 1,12-tridecadiene),tetradecadiene (e.g., 1,13-tetradecadiene), pentadecadiene,hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, icosadiene,heneicosadiene, docosadiene, tricosadiene, tetracosadiene,pentacosadiene, hexacosadiene, heptacosadiene, octacosadiene,nonacosadiene, triacontadiene, and polybutadienes having a molecularweight (Mw) of less than 1000 g/mol. Examples of straight chain acyclicdienes include, but are not limited to 1,4-hexadiene and 1,6-octadiene.Examples of branched chain acyclic dienes include, but are not limitedto 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, and3,7-dimethyl-1,7-octadiene. Examples of single ring alicyclic dienesinclude, but are not limited to 1,4-cyclohexadiene, 1,5-cyclooctadiene,and 1,7-cyclododecadiene. Examples of multi-ring alicyclic fused andbridged ring dienes include, but are not limited to tetrahydroindene;norbornadiene; methyltetrahydroindene; dicyclopentadiene;bicyclo(2.2.1)hepta-2,5-diene; and alkenyl-, alkylidene-, cycloalkenyl-,and cycloalkylidene norbornenes [including, e.g.,5-methylene-2-norbornene, 5-ethylidene-2-norbornene,5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene,5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene, and5-vinyl-2-norbornene]. Examples of cycloalkenyl-substituted alkenesinclude, but are not limited to vinyl cyclohexene, allyl cyclohexene,vinylcyclooctene, 4-vinylcyclohexene, allyl cyclodecene,vinylcyclododecene, and tetracyclododecadiene. In some embodiments ofthe present invention, the diene is selected from5-ethylidene-2-norbornene (ENB); 1,4-hexadiene; 5-methylene-2-norbornene(MNB); 1,6-octadiene; 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6-octadiene; 1,3-cyclopentadiene; 1,4-cyclohexadiene;vinyl norbornene (VNB); dicyclopentadiene (DCPD), and combinationsthereof. In one or more embodiments, the diene is ENB.

In other embodiments, the propylene-based polymer preferably comprisespropylene and one or more C2 and/or C4-C20 olefins. In general, thiswill amount to the propylene-based polymer preferably comprising fromabout 0.3 to about 40 wt. % of one or more C2 and/or C4-C20 olefinsbased the weight of the polymer. When C2 and/or C4-C20 olefins arepresent, the combined amount of these olefin-derived units in thepolymer is preferably at least about 1 wt. % and falling within theranges described herein. Other preferred ranges for the ethylene and/orone or more α-olefins include from about 0.5 wt. % to about 30 wt. %,more preferably from about 1 wt. % to about 25 wt. %, more preferablyfrom about 5 wt. % to about 25 wt. %, more preferably from about 5 wt. %to about 20 wt. %, more preferably from about 5 wt. % to about 17 wt. %and more preferably from about 5 wt. % to about 16 wt. %.

The propylene-based polymer can have a weight average molecular weight(Mw) of 5,000,000 or less, a number average molecular weight (Mn) ofabout 3,000,000 or less, a z-average molecular weight (Mz) of about10,000,000 or less, and a g′ index of 0.95 or greater measured at theweight average molecular weight (Mw) of the polymer using isotacticpolypropylene as the baseline, all of which can be determined by sizeexclusion chromatography, e.g., 3D SEC, also referred to as GPC-3D asdescribed herein.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a Mw of about 5,000 to about 5,000,000g/mole, more preferably a Mw of about 10,000 to about 1,000,000, morepreferably a Mw of about 20,000 to about 500,000, more preferably a Mwof about 50,000 to about 400,000, wherein Mw is determined as describedherein.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a Mn of about 2,500 to about 2,500,000g/mole, more preferably a Mn of about 5,000 to about 500,000, morepreferably a Mn of about 10,000 to about 250,000, more preferably a Mnof about 25,000 to about 200,000, wherein Mn is determined as describedherein.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a Mz of about 10,000 to about 7,000,000g/mole, more preferably a Mz of about 50,000 to about 1,000,000, morepreferably a Mz of about 80,000 to about 700,000, more preferably a Mzof about 100,000 to about 500,000, wherein Mz is determined as describedherein.

The molecular weight distribution index (MWD=(Mw/Mn)), sometimesreferred to as a “polydispersity index” (PDI), of the propylene-basedpolymer can be about 1.5 to 40. In an embodiment, the MWD can have anupper limit of 40, or 20, or 10, or 5, or 4.5, and a lower limit of 1.5,or 1.8, or 2.0. In one or more embodiments above or elsewhere herein,the MWD of the propylene-based polymer is about 1.8 to 5 and mostpreferably about 1.8 to 3. Techniques for determining the molecularweight (Mn and Mw) and molecular weight distribution (MWD) can be foundin U.S. Pat. No. 4,540,753 (Cozewith, Ju and Verstrate) (which isincorporated by reference herein for purposes of U.S. practices) andreferences cited therein, in Macromolecules, 1988, volume 21, p 3360(Verstrate et al.), which is herein incorporated by reference forpurposes of U.S. practice, and references cited therein, and inaccordance with the procedures disclosed in U.S. Pat. No. 6,525,157,Column 5, Lines 1-44, which patent is hereby incorporated by referencein its entirety.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a g′ index value of 0.95 or greater,preferably at least 0.98, with at least 0.99 being more preferred,wherein g′ is measured at the Mw of the polymer using the intrinsicviscosity of isotactic polypropylene as the baseline. For use herein,the g′ index is defined as:

$g^{\prime} = \frac{\eta_{b}}{\eta_{l}}$

where η_(b) is the intrinsic viscosity of the polymer and η_(l) is theintrinsic viscosity of a linear polymer of the same viscosity-averagedmolecular weight (Mv) as the polymer. η_(l)=KMv^(α), K and α aremeasured values for linear polymers and should be obtained on the sameinstrument as the one used for the g′ index measurement.

In one or more embodiments above or elsewhere herein, thepropylene-based is polymer can have a density of about 0.85 g/cm³ toabout 0.92 g/cm³, more preferably, about 0.87 g/cm³ to 0.90 g/cm³, morepreferably about 0.88 g/cm³ to about 0.89 g/cm³ at room temperature asmeasured per the ASTM D-1505 test method.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a melt flow rate (MFR, 2.16 kg weight @230° C.), equal to or greater than 0.2 g/10 min as measured according tothe ASTM D-1238(A) test method as modified (described below).Preferably, the MFR (2.16 kg @ 230° C.) is from about 0.5 g/10 min toabout 200 g/10 min and more preferably from about 1 g/10 min to about100 g/10 min. In an embodiment, the propylene-based polymer has an MFRof 0.5 g/10 min to 200 g/10 min, especially from 2 g/10 min to 30 g/10min, more preferably from 5 g/10 min to 30 g/10 min, more preferably 10g/10 min to 30 g/10 min, more preferably 10 g/10 min to about 25 g/10min, or more preferably 2 g/10 min to about 10 g/10 min.

The propylene-based polymer can have a Mooney viscosity ML (1+4)@125°C., as determined according to ASTM D1646, of less than 100, morepreferably less than 75, even more preferably less than 60, mostpreferably less than 30.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can have a heat of fusion (Hf) determinedaccording to the DSC procedure described later, which is greater than orequal to about 0.5 Joules per gram (J/g), and is ≦about 80 J/g,preferably ≦about 75 J/g, preferably ≦about 70 J/g, more preferably≦about 60 J/g, more preferably ≦about 50 J/g, more preferably ≦about 35J/g. Also preferably, the propylene-based polymer has a heat of fusionthat is greater than or equal to about 1 J/g, preferably greater than orequal to about 5 J/g. In another embodiment, the propylene-based polymercan have a heat of fusion (Hf), which is from about 0.5 J/g to about 75J/g, preferably from about 1 J/g to about 75 J/g, more preferably fromabout 0.5 J/g to about 35 J/g. Preferred propylene-based polymers andcompositions can be characterized in terms of both their melting points(Tm) and heats of fusion, which properties can be influenced by thepresence of comonomers or steric irregularities that hinder theformation of crystallites by the polymer chains. In one or moreembodiments, the heat of fusion is from a lower limit of 1.0 J/g, or 1.5J/g, or 3.0 J/g, or 4.0 J/g, or 6.0 J/g, or 7.0 J/g, to an upper limitof 30 J/g, or 35 J/g, or 40 J/g, or 50 J/g, or 60 J/g or 70 J/g, or 75J/g, or 80 J/g.

The crystallinity of the propylene-based polymer can also be expressedin terms of percentage of crystallinity (i.e. % crystallinity). In oneor more embodiments above or is elsewhere herein, the propylene-basedpolymer has a % crystallinity of from 0.5% to 40%, preferably 1% to 30%,more preferably 5% to 25% wherein % crystallinity is determinedaccording to the DSC procedure described below. In another embodiment,the propylene-based polymer preferably has a crystallinity of less than40%, preferably about 0.25% to about 25%, more preferably from about0.5% to about 22%, and most preferably from about 0.5% to about 20%. Asdisclosed above, the thermal energy for the highest order ofpolypropylene is estimated at 189 J/g (i.e., 100% crystallinity is equalto 209 J/g).

In addition to this level of crystallinity, the propylene-based polymerpreferably has a single broad melting transition. However, thepropylene-based polymer can show secondary melting peaks adjacent to theprincipal peak, but for purposes herein, such secondary melting peaksare considered together as a single melting point, with the highest ofthese peaks (relative to baseline as described herein) being consideredthe melting point of the propylene-based polymer.

The propylene-based polymer preferably has a melting point (measured byDSC) of equal to or less than 100° C., preferably less than 90° C.,preferably less than 80° C., more preferably less than or equal to 75°C., preferably from about 25° C. to about 80° C., preferably about 25°C. to about 75° C., more preferably about 30° C. to about 65° C.

The Differential Scanning calorimetry (DSC) procedure can be used todetermine heat of fusion and melting temperature of the propylene-basedpolymer. The method is as follows: about 0.5 grams of polymer is weighedout and pressed to a thickness of about 15-20 mils (about 381-508microns) at about 140° C.-150° C., using a “DSC mold” and Mylar as abacking sheet. The pressed pad is allowed to cool to ambient temperatureby hanging in air (the Mylar is not removed). The pressed pad isannealed at room temperature (23-25° C.) for about 8 days. At the end ofthis period, an about 15-20 mg disc is removed from the pressed padusing a punch die and is placed in a 10 microliter aluminum sample pan.The sample is placed in a Differential Scanning calorimeter (PerkinElmer Pyris 1 Thermal Analysis System) and is cooled to about −100° C.The sample is heated at 10° C./min to attain a final temperature ofabout 165° C. The thermal output, recorded as the area under the meltingpeak of the sample, is a measure of the heat of fusion and can beexpressed in Joules per gram of polymer and is automatically calculatedby the Perkin Elmer System. The melting point is recorded as thetemperature of the greatest heat absorption within the range of meltingof the sample relative to a baseline measurement for the increasing heatcapacity of the polymer as a function of temperature.

The propylene-based polymer can have a triad tacticity of threepropylene units, as measured by ¹³C NMR of 75% or greater, 80% orgreater, 82% or greater, 85% or greater, or 90% or greater. Preferredranges include from about 50% to about 99%, more preferably from about60% to about 99%, more preferably from about 75% to about 99% and morepreferably from about 80% to about 99%; and in other embodiments fromabout 60% to about 97%. Triad tacticity is determined by the methodsdescribed in U.S. Publication No. 2004/0236042.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can be a blend of discrete randompropylene-based polymers. Such blends can include ethylene-basedpolymers and propylene-based polymers, or at least one of each suchethylene-based polymers and propylene-based polymers. The number ofpropylene-based polymers can be three or less, more preferably two orless.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can include a blend of two propylene-basedpolymers differing in the olefin content, the diene content, or both.

In one or more embodiments above or elsewhere herein, thepropylene-based polymer can include a propylene based elastomericpolymer produced by random polymerization processes leading to polymershaving randomly distributed irregularities in stereoregular propylenepropagation. This is in contrast to block copolymers in whichconstituent parts of the same polymer chains are separately andsequentially polymerized.

In another embodiment, the propylene-based polymers can includecopolymers prepared according the procedures in WO 02/36651. Likewise,the propylene-based polymer can include polymers consistent with thosedescribed in WO 03/040201, WO 03/040202, WO 03/040095, WO 03/040201, WO03/040233, and/or WO 03/040442. Additionally, the propylene-basedpolymer can include polymers consistent with those described in EP1233191, and U.S. Pat. No. 6,525,157, along with suitable propylenehomo- and copolymers described in U.S. Pat. No. 6,770,713 and U.S.Patent Application Publication 2005/215964, all of which areincorporated by reference. The propylene-based polymer can also includeone or more polymers consistent with those described in EP 1614699 or EP1017729.

Polymer Blend

In one or more embodiments, the propylene-based polymer can comprise ais polymer blend of two propylene-based polymers (“first polymer” and“second polymer”) differing in the olefin content and substantiallylacking diene-derived units.

In some embodiments of the present invention, the first and secondpolymers are each a copolymer of propylene and one or more comonomers.The comonomers may be linear or branched. In one or more embodiments,linear comonomers may include ethylene or C₄ to C₈ α-olefins, includingbut not limited to 1-butene, 1-hexene, and 1-octene. Branched comonomersmay include 4-methyl-1-pentene, 3-methyl-1-pentene, and3,5,5-trimethyl-1-hexene. In one or more embodiments, the comonomer caninclude styrene.

In some embodiments, the first and second polymers are each a copolymerof propylene and ethylene (and may comprise other comonomers as well).For example, the first and second polymers may be the same or different,and may each comprise from about 75 wt. % to about 99 wt. % unitsderived from propylene and from about 1 wt. % to about 25 wt. % unitsderived from ethylene. In some embodiments, the first polymer maycomprise from about 12 wt. % to about 20 wt. % ethylene-derived units,or from about 14 wt. % to about 18 wt. % ethylene-derived units. In thesame or other embodiments, the second polymer may comprise from about 3wt. % to about 10 wt. % ethylene-derived units, or from about 5 wt. % toabout 8 wt. % ethylene-derived units. In one embodiment of the presentinvention, the first polymer has greater ethylene content than thesecond polymer. For example, the first polymer may comprise at least 3wt. %, or at least 5 wt. %, or at least 7 wt. %, or at least 9 wt. %more ethylene-derived units than the second polymer. In the same orother embodiment, the polymer blend comprises from about 1 wt. % toabout 25 wt. %, from about 5 wt. % to about 20 wt. %, or from about 10wt. % to about 18 wt. % ethylene-derived units based on the weight ofthe polymer blend.

In one or more embodiments herein, the second polymer may alternatelycomprise lower amounts of ethylene, or no ethylene at all, such that thesecond polymer may be homopolypropylene or a random copolymer ofpolypropylene (RCP). Exemplary RCPs typically comprise from about 1 wt.% to about 8 wt. % comonomer, or from about 2 to about 5 wt. %comonomer. In one or more embodiments, the RCP comonomer is ethylene.

In one or more embodiments, the first and second polymers may have aweight average molecular weight (Mw) of 5,000,000 g/mole or less, anumber average molecular weight (Mn) of about 3,000,000 g/mole or less,a z-average molecular weight (Mz) of about 10,000,000 g/mole or less,and a g′ index of 0.95 or greater measured at the weight averagemolecular weight (Mw) of the polymer using isotactic polypropylene asthe baseline, all of is which can be determined by size exclusionchromatography, e.g., 3D SEC, also referred to as GPC-3D.

In one or more embodiments, the first and second polymers have the sameor different Mw, and each have an Mw of about 5,000 to about 5,000,000g/mole, or an Mw of about 10,000 to about 1,000,000, or an Mw of about20,000 to about 500,000, or an Mw of about 50,000 to about 400,000,where Mw is determined as described herein.

In one or more embodiments, the first and second polymers may have thesame or different Mn, and each have an Mn of about 2,500 to about2,500,000 g/mole, or an Mn of about 5,000 to about 500,000, or an Mn ofabout 10,000 to about 250,000, or an Mn of about 25,000 to about200,000, where Mn is determined as described herein.

In one or more embodiments, the first and second polymers have the sameor different Mz, and each have an Mz of about 10,000 to about 7,000,000g/mole, or an Mz of about 50,000 to about 1,000,000, or an Mz of about80,000 to about 700,000, or an Mz of about 100,000 to about 500,000,where Mz is determined as described herein.

In some embodiment the MWD can have an upper limit of 40, or 20, or 10,or 5, or 4.5, and a lower limit of 1.5, or 1.8, or 2.0. In one or moreembodiments, the MWD of the first polymer or the second polymer or bothis about 1.8 to 5. Method of determination of molecular weight andmolecular weight distribution is as aforementioned.

In one or more embodiments, the first and second polymers may have a g′index value of 0.95 or greater, or at least 0.97, or at least 0.99,wherein g′ index is measured at the Mw of the polymer using theintrinsic viscosity of isotactic polypropylene as the baseline, asmentioned above.

In one or more embodiments, the first and second polymers may have thesame or different density, which may be from about 0.85 g/cm³ to about0.92 g/cm³, or from about 0.87 g/cm³ to 0.90 g/cm³, or from about 0.88g/cm³ to about 0.89 g/cm³ at room temperature as measured per the ASTMD-1505 test method.

In one or more embodiments, the first and second polymers can have amelt flow rate (MFR, 2.16 kg weight @ 230° C.) greater than or equal to0.2 g/10 min as measured according to the ASTM D-1238(A) test method.The MFR of the first and second polymers can be the same or different.In some embodiments, the MFR (2.16 kg @ 230° C.) of the first polymer orthe second polymer or both is from about 0.5 g/10 min to about 200 g/10min, or from about 1 g/10 min to about 100 g/10 min. In someembodiments, the first and/or second is polymers have an MFR of fromabout 0.5 g/10 min to about 200 g/10 min, or from about 2 g/10 min toabout 30 g/10 min, or from about 5 g/10 min to about 30 g/10 min, orfrom about 10 g/10 min to about 30 g/10 min, or from about 10 g/10 minto about 25 g/10 min, or from about 2 g/10 min to about 10 g/10 min.

The first and/or second polymers may have a Mooney viscosity, ML(1+4)@125° C., as determined according to ASTM D1646, of less than 100,or less than 75, or less than 60, or less than 30. The Mooney viscosityof the first and second polymers may be the same or different.

In one or more embodiments, the first polymer or second polymer or bothmay have a heat of fusion (Hf) determined according to the DSC proceduredescribed later, which is greater than or equal to about 0.5 Joules pergram (J/g), and is less than or equal to about 80 J/g, or less than orequal to about 75 J/g, or less than or equal to about 70 J/g, or lessthan or equal to about 60 J/g, or less than or equal to about 50 J/g.The first polymer or second polymer or both may also have a heat offusion that is greater than or equal to about 1 J/g, or greater than orequal to about 5 J/g. In another embodiment, the first polymer or secondpolymer or both may have a heat of fusion (Hf) which is from about 0.5J/g to about 75 J/g, or from about 1 J/g to about 75 J/g, or from about3 J/g to about 35 J/g. In some embodiments, the first and secondpolymers can be characterized in terms of both their melting points (Tm)and heats of fusion, which properties can be influenced by the presenceof comonomers or steric irregularities that hinder the formation ofcrystallites by the polymer chains. In one or more embodiments, the heatof fusion of the first polymer or the second polymer or both ranges froma lower limit of 1.0 J/g, or 1.5 J/g, or 3.0 J/g, or 4.0 J/g, or 6.0J/g, or 7.0 J/g, to an upper limit of 30 J/g, or 35 J/g, or 40 J/g, or50 J/g, or 60 J/g or 70 J/g, or 75 J/g, or 80 J/g. The heat of fusion ofthe first and second polymers may be the same or different.

The crystallinity of the first and second polymers can also be expressedin terms of percentage of crystallinity (i.e., % crystallinity). In oneor more embodiments, the first polymer and second polymers have the sameor different crystallinity, and the % crystallinity of one or both ofthe polymers may be from 0.5% to 40%, or from 1% to 30%, or from 5% to25%, where % crystallinity is determined according to the DSC proceduredescribed above.

The first and second polymers may have the same or different meltingpoint, and, in some embodiments, one or both of the first and secondpolymers, has a melting point (measured by DSC) of equal to or less than110° C., or less than 100° C., or less than 90° C., or is less than orequal to 80, or less than or equal to 75° C., or from about 25° C. toabout 80° C., or from about 25° C. to about 75° C., or from about 30° C.to about 65° C. In one or more embodiments, the melting point of thesecond polymer is greater than the melting point of the first polymer,and may be greater than about 105° C., or greater than about 110° C., orgreater than about 115° C.

The first and/or second polymers may further have a triad tacticity ofthree propylene units, as measured by ¹³C NMR, of 75% or greater, 80% orgreater, 82% or greater, 85% or greater, or 90% or greater. In someembodiments, the triad tacticity of the first polymer, the secondpolymer, or both ranges from about 50 to about 99%, or from about 60 toabout 99%, or from about 75 to about 99%, or from about 80 to about 99%,or from about 60 to about 97%. Triad tacticity can be determined asaforementioned.

Preparation of the Polymer Blend

Particles made from polymers of the type described herein are generallysoft to the touch and may be tacky. While these properties are desirablefor many end-use applications, the polymers may present storage andhandling problems. For example, polymer particles, such as those madefrom a pelletization process, made from these polymers have a tendencyto agglomerate (or exhibit restricted flow), particularly afterlong-term warehouse storage at ambient temperatures.

It has been discovered that agglomeration of these pellets results fromdeformation of the polymer pellets during storage and handling of thepellets during the first few hours or days following production of thepellets. Specifically, upon production, polymer pellets generally haveshapes that are spherical, cylindrical, disk-like, or other shapes inwhich the outer surface of the pellets are curved as opposed to flatsurfaces. Generally, polymer pellets are free-flowing, as the curvedsurfaces of the pellets have minimal contact surface and thus slidefreely past each other. However, it has been discovered that undercertain circumstances, the curved pellet surfaces may become flattenedduring storage as a result of the pellets pressing against each other,especially when stored in containers with significant verticaldimensions. When this flattening of the surfaces of the polymer pelletsoccurs, contact area increases significantly, reducing the ability ofthe pellet surfaces to slide past each other, leading to agglomerationor restricted flow of the particles in subsequent processing steps.

By increasing the rate of crystallization, flattening of the surfaces ofthe pellets is is less likely to occur and the pellets can become hardin the course of conventional polymer finishing steps to providefree-flowing pellets, even after the pellets are stored for long periodsof time at high ambient temperatures.

The resistance of a pellet to flattening of its surfaces is related tothe level of crystallization of the polymers and may be determined bymeasuring the hardness of the polymer pellets. Generally, it has beendetermined, in one embodiment, that a Shore A Hardness (ASTM 2240) of atleast 50 provides pellets with a reduced tendency to agglomerate. Inanother embodiment, a Shore A Hardness of at least 55 provides pelletswith a reduced tendency to agglomerate. In a further embodiment, a shoreA Hardness of at least 60 provides pellets with a reduced tendency toagglomerate. While pellets made from many low crystallinity polymers mayachieve this level of hardness following production, it may take daysbefore this level of hardness is attained as the pellets crystallizeslowly over time, particularly for propylene-based polymers andcopolymers where crystallization kinetics are known to be slower thanethylene-based polymers and copolymers. The processes described hereinare believed to speed the rate of crystallization of the polymer pelletsto provide hardness, in a short period of time after production, whichenables the pellets to flow freely, even after long storage periods.

In certain embodiments of the processes and blends described herein, afirst polymer is blended with a second polymer to produce a polymerblend that, when processed into pellet forms, will achieve a state ofcrystallization sufficient to provide a Shore A hardness of at least 50,or at least 52, or at least 55, or at least 57, or at least 60, in arelatively short period time (i.e., within 40 minutes after initialcooling of the pellets, or within 30 minutes, or within 20 minutes, orwithin 15 minutes), as compared to pellets produced from the firstpolymer alone.

For purposes of this disclosure, the first polymer, as described above,may generally be considered a low crystallinity polymer, while thesecond polymer, as described above, may generally be considered a highcrystallinity polymer. It has been discovered that the agglomerationtendencies of pellets made from low crystallinity polymers may bereduced or eliminated by blending the low crystallinity polymer with atleast one high crystallinity polymer incorporating propylene-derivedunits having high crystallinity. For purposes of this disclosure, a highcrystallinity polymer incorporating propylene-derived units means apolymer incorporating at least 90 wt. % of propylene derived units andhaving a melt temperature of at least 100° C.

In certain embodiments of the processes and blends described herein,solutions of a first low crystallinity polymer and a second highcrystallinity polymer are blended via a process which produces thepolymers in separate series or parallel polymerization stages. Forexample, the first low crystallinity polymer may be produced in a firstreactor. An effluent from the first reactor, containing a solution ofthe first polymer, is transferred to a second reactor where a catalystand monomers necessary to produce the second high crystallinity polymerare contacted, so that a solution of the second polymer is produced inthe second reactor and in the presence of the first polymer. This isreferred to as a series reactor process.

Both the first polymer and the second polymer may be produced insolution polymerization reactors. Combining the solutions of thepolymeric components resulting from these processes provides an intimateblending of the first and second polymers during polymerization of thesecond copolymer. The blended polymers may then be withdrawn from thesecond reactor and processed into polymer particles, fibers, films,nonwovens, or other finished articles using conventional processingequipment and techniques.

Alternatively, the first low crystallinity polymer may be produced inthe first reactor in parallel with the second high crystallinity polymerproduced in the second reactor. In parallel polymerization processes,the first and second polymers are produced in parallel reactors witheffluents from each reactor, containing solutions of the respectivepolymer, directed to a device for blending the effluents to produce asolution of blended polymer components. The blended polymers are thenrecovered from the solution and processed into polymer particles,fibers, films, nonwovens, or other finished articles in accordance withconventional process equipment and techniques.

More detailed descriptions of both series and parallel processessuitable for production of the polymer blends described herein,including polymerization conditions and suitable catalysts for usetherein, are found in U.S. Publication No. 2004/0024146 and U.S.Publication No. 2006/0183861, both of which are incorporated byreference herein in their entireties.

In alternate embodiments of the present invention, the first and secondpolymers may be produced in high pressure solution processes. Suchprocesses, including polymerization conditions and suitable catalystsfor use therein, are described in more detail in U.S. Publication No.2009/0163642, which is incorporated by reference herein in its entirety.

In some embodiments of the present invention, polymer blends of theinvention is are produced by polymerizing a polymer solution comprisinga first polymer in a first reactor, polymerizing a polymer solutioncomprising a second polymer in a second reactor, combining the firstpolymer solution with the second polymer solution to produce a polymerblend solution, and processing the polymer blend solution to produce apolymer blend.

Properties of the Polymer Blend

In certain embodiments of the present invention, the polymer blendsproduced by the dual reactor process described above may incorporate, inneat form, from about 45 wt. % to about 98 wt. %, or from about 50 wt. %to about 98 wt. %, or from about 60 wt. % to about 98 wt. %, or fromabout 70 wt. % to about 98 wt. % of the first polymer and from about 2wt. % to about 55 wt. %, or from about 2 wt. % to about 50 wt. %, orfrom about 2 wt. % to about 40 wt. %, or from about 2 wt. % to about 30wt. % of the second polymer. In another embodiment, in neat form, thepolymer blends described herein incorporate from about 80 wt. % to about95 wt. % of the first polymer and from about 5 wt. % to about 20 wt. %of the second polymer. In other embodiments, in neat form, the polymerblends described herein incorporate from about 90 wt. % to about 95 wt.% of the first polymer and from about 5 wt. % to about 10 wt. % of thesecond polymer.

In further embodiments of the invention, the polymer blends may comprisean overall ethylene content of from about 10 wt. % to about 18 wt. %, orfrom about 12 wt. % to about 16 wt. % ethylene.

In some embodiments, the polymer blends described herein may have a meltflow rate (MFR, 2.16 kg weight @ 230° C.) of from about 1 to about 30g/10 min, as measured according to the ASTM D-1238(A) test method. Infurther embodiments, the MFR of the blend is from about 3 to about 7g/10 min.

In some embodiments, the polymer blends may have an Mn of from about10,000 to about 200,000 g/mole, or from about 20,000 to about 150,000,or from about 30,000 to about 100,000. In the same or other embodiments,the polymer blends may have an Mw of from about 100,000 to about 400,000g/mole, or from about 150,000 to about 300,000, or from about 200,000 toabout 250,000. The polymer blends may also have an MWD of from about 1.5to about 10, or from about 2.0 to about 4.0. In addition, the polymerblends may have a g′ index of from about 0.94 to about 0.99, or fromabout 0.95 to about 0.98.

The polymer blends described herein may, in some embodiments, have amelting point greater than about 100° C., or greater than about 110° C.,or greater than about 115° C. In addition, the heat of fusion of thepolymer blends may be less than about 30 J/g, or less than is about 25J/g, or less than about 20 J/g. In some embodiments of the presentinvention, the polymer blends prepared in dual reactors as describedabove have a melting point that is at least about 5° C. greater, or atleast about 10° C. greater, than the melting point of a polymer blendhaving the same overall composition but prepared by physically blendingthe first and second polymers rather than by reactor blending.

Grafted (Functionalized) Backbone

In one or more embodiments, the propylene-based polymer can be grafted(i.e., “functionalized”) using one or more grafting monomers. As usedherein, the term “grafting” denotes covalent bonding of the graftingmonomer to a polymer chain of the propylene-based polymer.

The grafting monomer can be or include at least one ethylenicallyunsaturated carboxylic acid or acid derivative, such as an acidanhydride, ester, salt, amide, imide, acrylates, or the like.Illustrative monomers include but are not limited to acrylic acid,methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconicacid, mesaconic acid, maleic anhydride, 4-methylcyclohexene-1,2-dicarboxylic acid anhydride,bicyclo(2.2.2)octene-2,3-dicarboxylic acid anhydride,1,2,3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic acid anhydride,2-oxa-1,3-diketospiro(4.4)nonene, bicyclo(2.2.1)heptene-2,3-dicarboxylicacid anhydride, maleopimaric acid, tetrahydrophthalic anhydride,norbornene-2,3-dicarboxylic acid anhydride, nadic anhydride, methylnadic anhydride, himic anhydride, methyl himic anhydride, and5-methylbicyclo(2.2.1)heptene-2,3-dicarboxylic acid anhydride. Othersuitable grafting monomers include methyl acrylate and higher alkylacrylates, methyl methacrylate and higher alkyl methacrylates, acrylicacid, methacrylic acid, hydroxy-methyl methacrylate, hydroxyl-ethylmethacrylate and higher hydroxy-alkyl methacrylates and glycidylmethacrylate. Maleic anhydride is a preferred grafting monomer.

In one or more embodiments, the grafted propylene based polymercomprises from about 0.5 to about 10 wt. % ethylenically unsaturatedcarboxylic acid or acid derivative, more preferably from about 0.5 toabout 6 wt. %, more preferably from about 0.5 to about 3 wt. %; in otherembodiments from about 1 to about 6 wt. %, more preferably from about 1to about 3 wt. %. In a preferred embodiment wherein the graft monomer ismaleic anhydride, the maleic anhydride concentration in the graftedpolymer is preferably in the range of about 1 to about 6 wt. %,preferably at least about 0.5 wt. % and highly preferably about 1.5 wt.%.

Styrene and derivatives thereof, such as paramethyl styrene, or otherhigher alkyl substituted styrenes, such as t-butyl styrene, can be usedas a charge transfer agent in is presence of the grafting monomer toinhibit chain scissioning. This allows further minimization of the betascission reaction and the production of a higher molecular weightgrafted polymer (MFR=1.5).

Preparing Grafted Propylene-Based Polymers

The grafted propylene-based polymer can be prepared using conventionaltechniques. For example, the graft polymer can be prepared in solution,in a fluidized bed reactor, or by melt grafting. A preferred graftedpolymer can be prepared by melt blending in a shear-imparting reactor,such as an extruder reactor. Single screw, preferably twin screwextruder reactors, such as co-rotating intermeshing extruder, orcounter-rotating non-intermeshing extruders but also co-kneaders, suchas those sold by Buss, are especially preferred.

In one or more embodiments, the grafted polymer can be prepared by meltblending the ungrafted propylene-based polymer with a free radicalgenerating catalyst, such as a peroxide initiator, in the presence ofthe grafting monomer. The preferred sequence for the grafting reactionincludes melting the propylene-based polymer, adding and dispersing thegrafting monomer, introducing the peroxide and venting the unreactedmonomer and by-products resulting from the peroxide decomposition. Othersequences can include feeding the monomers and the peroxidepre-dissolved in a solvent.

Illustrative peroxide initiator include but are not limited to: diacylperoxides such as benzoyl peroxide; peroxyesters such astert-butylperoxy benzoate, tert-butylperoxy acetate,OO-tert-butyl-O-(2-ethylhexyl)monoperoxy carbonate; peroxyketals such asn-butyl-4,4-di-(tert-butyl peroxy) valerate; and dialkyl peroxides suchas 1,1-bis(tertbutylperoxy)cyclohexane,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,2,2-bis(tert-butylperoxy)butane, dicumylperoxide,tert-butylcumylperoxide, Di-(2-tert-butylperoxy-isopropyl-(2))benzene,di-tert-butylperoxide (DTBP),2,5-dimethyl-2,5-di(tert-butylperoxy)hexane,2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne, 3,3,5,7,7-pentamethyl1,2,4-trioxepane; and the like.

Composition

In some embodiments of the present invention, the propylene-basedpolymers, including the polymer blends described herein, may becompounded with one or more additional components. Additional componentssuitable for compounding with the polymer blend are well known topersons of skill in the art and may include, but are not limited to, iscoagents, antioxidants, secondary elastomers, polyolefinic thermoplasticresins, such as polypropylene, additives, fillers, and additive oils. Infurther embodiments, the propylene-based polymers, including the polymerblends, are compounded with at least one or more coagents or one or moreantioxidants, with or without other additional components. In certainembodiments, the propylene-based polymers, including the polymer blendsdescribed herein, are compounded with both a coagent and an antioxidant.

In one or more embodiments, the individual materials and components,such as the propylene-based polymers, including the polymer blendsdescribed herein, and optionally the one or more coagents, antioxidants,secondary elastomers, polyolefinic thermoplastics, such aspolypropylene, additives, fillers, and/or additive oils may be blendedby melt-mixing to form a composition. Examples of machinery capable ofgenerating the required shear and mixing for compounding includeextruders with kneaders or mixing elements with one or more mixing tipsor flights, extruders with one or more screws, extruders of co orcounter rotating type, Banbury mixers, Farrell Continuous mixers, andBuss Kneaders. The type and intensity of mixing, temperature, andresidence time required can be achieved by the choice of one of theabove machines in combination with the selection of kneading or mixingelements, screw design, and screw speed (<3000 RPM).

In one or more embodiments, the coagents, antioxidants, and/or otheradditives can be introduced at the same time as the other polymercomponents or later downstream, in the case of using an extruder or Busskneader, or only later in time. In further embodiments, when polymerblends described herein are used, the coagents, antioxidants, and/orother additives may be incorporated into the polymer product by in-linecompounding, in which the additives are introduced into the secondreactor at the time the second polymer is formed. This eliminates theneed for additional compounding steps and equipment. In addition to thecoagents and antioxidants described, other additives can include, butare not limited to, antiblocking agents, antistatic agents, ultravioletstabilizers, pigments, coloring agents, nucleating agents, fire or flameretardants, plasticizers, vulcanizing or curative agents, vulcanizing orcurative accelerators, tackifiers, flow improvers, lubricants, moldrelease agents, foaming agents, reinforcers, and processing aids. Theadditives can be added to the blend in pure form or in master batches.Fillers suitable for use in the compounded polymer blends of the presentinvention are well known in the art and may include granular, fibrous,and powder-like fillers. Particular fillers which may be suitable foruse in the present invention include natural and synthetic clays, carbonblack, and diatomaceous earth, among is others.

Illustrative ingredients that may be included in the composition are setforth in greater detail below, but persons of skill in the art willrecognize that the following description is not inclusive, and that anymaterial suitable for compounding with the polymer blends describedherein may be employed.

Coagents

The composition of the present invention can optionally include one ormore coagents. Suitable coagents may include liquid and metallicmultifunctional acrylates and methacrylates, functionalizedpolybutadiene resins, functionalized cyanurate, and allyl isocyanurate.More particularly, suitable coagents can include, but are not limited topolyfunctional vinyl or allyl compounds such as, for example, triallylcyanurate, triallyl isocyanurate, pentaerthritol tetramethacrylate,ethylene glycol dimethacrylate, diallyl maleate, dipropargyl maleate,dipropargyl monoallyl cyanurate, azobisisobutyronitrile and the like,and combinations thereof. In one or more embodiments, suitable coagentsinclude triacrylates, and in a particular embodiment the coagent istrimethylolpropane trimethacrylate. Commercially available coagents maybe purchased from, for example, Sartomer. An exemplary coagent isSartomer 350.

In one or more embodiments, the polymer blends contain at least 0.1 wt.% of coagent based on the total weight of blend. In one or moreembodiments, the amount of coagent(s) can range from about 0.1 wt. % toabout 15 wt. %, based on the weight of blend. In one or moreembodiments, the amount of coagent(s) can range from a low of about 0.1wt. %, or about 0.5 wt. %, or about 1 wt. %, or about 1.5 wt. %, orabout 2 wt. % to a high of about 4 wt. %, or about 5 wt. %, or about 7wt. %, or about 10 wt. %, or about 15 wt. %, based on the weight of thecomposition. In further embodiments, the amount of coagent(s) is fromabout 3 wt. % to about 6% based on the total weight of the composition.

Antioxidants

The composition of the present invention may optionally include one ormore anti-oxidants. Examples of antioxidants include, but are notlimited to quinolein, e.g., trimethylhydroxyquinolein (TMQ); imidazole,e.g., zincmercapto toluoyl imidazole (ZMTI); and conventionalantioxidants, such as hindered phenols, lactones, phosphates, andhindered amines. Further suitable anti-oxidants are commerciallyavailable from, for example, Ciba Geigy Corp. under the tradenamesIrgafos 168, Irganox 1010, Irganox 3790, Irganox B225, Irganox 1035,Irgafos 126, Irgastab 410, and Chimassorb 944. In one or moreembodiments, is the antioxidant comprises a phosphite ester, and mayparticularly be tris-(2,4-di-tert-butylphenyl)phosphite. The one or moreantioxidants may be added to the polymer blends to protect againstdegradation during shaping or fabrication operations and/or to bettercontrol the extent of chain degradation.

In one or more embodiments, the compositions contain at least 0.1 wt. %of antioxidant, based on the total weight of blend. In one or moreembodiments, the amount of antioxidant(s) can range from about 0.1 wt. %to about 5 wt. %, based on the total weight of blend. In otherembodiments, the amount of antioxidant(s) can range from a low of about0.1 wt. %, 0.15 wt. % or 0.2 wt. % to a high of about 1 wt. %, 2.5 wt.%, or 5 wt. %, based on the total weight of blend. In furtherembodiments, the amount of antioxidant(s) is from about 0.2 wt. % toabout 6 wt. %, based on the total weight of the composition.

Secondary Elastomers

The polymer blends of the present invention can optionally include oneor more secondary elastomers. In at least one specific embodiment, thesecondary elastomer can be or include one or more ethylene-propylenecopolymers (EP). Preferably, the ethylene-propylene polymer (EP) isnon-crystalline, e.g., atactic or amorphous, but in certain embodimentsthe EP may be crystalline (including “semi-crystalline”). Thecrystallinity of the EP is preferably derived from the ethylene, and anumber of published methods, procedures and techniques are available forevaluating whether the crystallinity of a particular material is derivedfrom ethylene. The crystallinity of the EP can be distinguished from thecrystallinity of the propylene-based polymer by removing the EP from thecomposition and then measuring the crystallinity of the residualpropylene-based polymer. Such crystallinity measured is usuallycalibrated using the crystallinity of polyethylene and related to thecomonomer content. The percent crystallinity in such cases is measuredas a percentage of polyethylene crystallinity and thus the origin of thecrystallinity from ethylene is established.

In one or more embodiments, the EP can include one or more optionalpolyenes, including particularly a diene; thus, the EP can be anethylene-propylene-diene terpolymer (commonly called “EPDM”). Theoptional polyene is considered to be any hydrocarbon structure having atleast two unsaturated bonds wherein at least one of the unsaturatedbonds is readily incorporated into a polymer. The second bond maypartially take part in polymerization to form long chain branches butpreferably provides at least some unsaturated bonds suitable forsubsequent curing or vulcanization in post polymerization processes.Examples of EP or EPDM copolymers include those that are available underthe trade name Vistalon from ExxonMobil Chemicals. Several commercialEPDMs are available from DOW under the tradenames Nordel IP and MG.Certain rubber components (e.g., EPDMs, such as Vistalon 3666) includeadditive oil that is preblended before the rubber component is combinedwith the thermoplastic. The type of additive oil utilized will be thatcustomarily used in conjunction with a particular rubber component.

Examples of the optional polyenes include, but are not limited to,butadiene; pentadiene; hexadiene (e.g., 1,4-hexadiene); heptadiene(e.g., 1,6-heptadiene); octadiene (e.g., 1,7-octadiene); nonadiene(e.g., 1,8-nonadiene); decadiene (e.g., 1,9-decadiene); undecadiene(e.g., 1,10-undecadiene); dodecadiene (e.g., 1,11-dodecadiene);tridecadiene (e.g., 1,12-tridecadiene); tetradecadiene (e.g.,1,13-tetradecadiene); pentadecadiene; hexadecadiene; heptadecadiene;octadecadiene; nonadecadiene; icosadiene; heneicosadiene; docosadiene;tricosadiene; tetracosadiene; pentacosadiene; hexacosadiene;heptacosadiene; octacosadiene; nonacosadiene; triacontadiene; andpolybutadienes having a molecular weight (Mw) of less than 1000 g/mol.Examples of straight chain acyclic dienes include, but are not limitedto 1,4-hexadiene and 1,6-octadiene. Examples of branched chain acyclicdienes include, but are not limited to 5-methyl-1,4-hexadiene,3,7-dimethyl-1,6-octadiene, and 3,7-dimethyl-1,7-octadiene. Examples ofsingle ring alicyclic dienes include, but are not limited to1,4-cyclohexadiene, 1,5-cyclooctadiene, and 1,7-cyclododecadiene.Examples of multi-ring alicyclic fused and bridged ring dienes include,but are not limited to tetrahydroindene; norbornadiene;methyltetrahydroindene; dicyclopentadiene;bicyclo(2.2.1)hepta-2,5-diene; and alkenyl-; alkylidene-; cycloalkenyl-;and cylcoalkyliene norbornenes [including, e.g.,5-methylene-2-norbornene; 5-ethylidene-2-norbornene;5-propenyl-2-norbornene; 5-isopropylidene-2-norbornene;5-(4-cyclopentenyl)-2-norbornene; 5-cyclohexylidene-2-norbornene; and5-vinyl-2-norbornene]. Examples of cycloalkenyl-substituted alkenesinclude, but are not limited to vinyl cyclohexene; allyl cyclohexene;vinylcyclooctene; 4-vinylcyclohexene; allyl cyclodecene;vinylcyclododecene; and tetracyclododecadiene.

In another embodiment, the secondary elastomer can include, but is notlimited to, styrene/butadiene rubber (SBR); styrene/isoprene rubber(SIR); styrene/isoprene/butadiene rubber (SIBR);styrene-butadiene-styrene block copolymer (SBS); hydrogenatedstyrene-ethylene/butylene-styrene block copolymer (SEBS); hydrogenatedstyrene-ethylene block copolymer (SEB); styrene-isoprene-styrene blockcopolymer (SIS); styrene-isoprene block copolymer (SI); hydrogenatedstyrene-isoprene block copolymer (SEP); hydrogenatedstyrene-isoprene-styrene block copolymer (SEPS);styrene-ethylene/butylene-ethylene block copolymer (SEBE);styrene-ethylene-styrene block copolymer (SES);ethylene-ethylene/butylene block copolymer (EEB);ethylene-ethylene/butylene/styrene block copolymer (hydrogenated BR-SBRblock copolymer); ethylene-ethylene/butylene-ethylene block copolymer(EEBE); ethylene-ethylene/alpha-olefin block copolymers; polyisoprenerubber; polybutadiene rubber; isoprene butadiene rubber (IBR);polysulfide; nitrile rubber; propylene oxide polymers; star-branchedbutyl rubber and halogenated star-branched butyl rubber; brominatedbutyl rubber; chlorinated butyl rubber; star-branched polyisobutylenerubber; star-branched brominated butyl (polyisobutylene/isoprenecopolymer) rubber; poly(isobutylene-co-alkylstyrene); preferablyisobutylene/methylstyrene copolymers such asisobutylene/meta-bromomethylstyrene; isobutylene/bromomethylstyrene;isobutylene/chloromethylstyrene; halogenated isobutylenecyclopentadiene; and isobutylene/chloromethylstyrene, and mixturesthereof. Preferred secondary elastomers include hydrogenatedstyrene-ethylene/butylene-styrene block copolymer (SEBS), andhydrogenated styrene-isoprene-styrene block copolymer (SEPS).

The secondary elastomer can also be or include natural rubber. Naturalrubbers are described in detail by Subramaniam in RUBBER TECHNOLOGY, pp.179-208 (1995). Suitable natural rubbers may be Malaysian rubbers suchas SMR CV, SMR 5, SMR 10, SMR 20, and SMR 50 and mixtures thereof,wherein the natural rubbers have a Mooney viscosity at 100° C. (ML 1+4)of from 30 to 120, more preferably from 40 to 65. The Mooney viscositytest referred to herein is in accordance with ASTM D-1646.

The secondary elastomer can also be or include one or more syntheticrubbers. Suitable commercially available synthetic rubbers includeNATSYN™ (Goodyear Chemical Company), and BUDENE™ 1207 or BR 1207(Goodyear Chemical Company). A desirable rubber is highcis-polybutadiene (cis-BR). By “cis-polybutadiene” or “highcis-polybutadiene”, it is meant that 1,4-cis polybutadiene is used,wherein the amount of cis component is at least 95%. An example of ahigh cis-polybutadiene commercial product is BUDENE™ 1207.

The secondary elastomer can be present in an amount of up to 50 phr inone embodiment, or up to 40 phr in another embodiment, or up to 30 phrin yet another embodiment. In one or more embodiments, the amount of thesecondary elastomer can range from a low of about 1, 7, or 20 phr to ahigh of about 25, 35, or 50 phr.

Polyolefinic Thermoplastic Resin

The composition can further comprise, in addition to the propylene-basedpolymer or polymer blends described herein, a polyolefinic thermoplasticresin. The term “polyolefinic thermoplastic resin” as used herein refersto any material that is not a rubber and that is a polymer or polymerblend having a melting point of 70° C. or more and considered by personsskilled in the art as being thermoplastic in nature, e.g., a polymerthat softens when exposed to heat and returns to its original conditionwhen cooled to room temperature. The polyolefinic thermoplastic resincan contain one or more polyolefins, including polyolefin homopolymersand polyolefin copolymers. Except as stated otherwise, the term“copolymer” means a polymer derived from two or more monomers (includingterpolymers, tetrapolymers, etc.), and the term “polymer” refers to anycarbon-containing compound having repeat units from one or moredifferent monomers.

Illustrative polyolefins can be prepared from mono-olefin monomersincluding, but are not limited to, monomers having 2 to 7 carbon atoms,such as ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene,1-octene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene,mixtures thereof and copolymers thereof with (meth)acrylates and/orvinyl acetates. Preferably, the polyolefinic thermoplastic resin isunvulcanized or non-crosslinked.

In one or more embodiments, the polyolefinic thermoplastic resindescribed herein may contain additional amounts of polypropylene. Theterm “polypropylene” as used herein broadly means any polymer that isconsidered a “polypropylene” by persons skilled in the art (as reflectedin at least one patent or publication), and includes homo, impact, andrandom polymers of propylene. Preferably, the polypropylene used in thecompositions described herein has a melting point above 110° C.,includes at least 90 wt. % propylene units, and contains isotacticsequences of those units. The polypropylene can also include atacticsequences or syndiotactic sequences, or both. The polypropylene can alsoinclude syndiotactic sequences such that the melting point of thepolypropylene is above 110° C. The polypropylene can either deriveexclusively from propylene monomers (i.e., having only propylene units)or derive from mainly propylene (more than 80% propylene) with theremainder derived from olefins, particularly ethylene, and/or C₄-C₁₀alpha-olefins. As noted elsewhere herein, certain polypropylenes have ahigh MFR (e.g., from a low of 10, or 15, or g/10 min to a high of 25 to30 g/10 min) Others have a lower MFR, e.g., “fractional” polypropyleneswhich have an MFR less than 1.0. Those with high MFR may be preferredfor ease of processing or compounding.

In one or more embodiments, the polyolefinic thermoplastic resin mayinclude isotactic polypropylene. Preferably, the polyolefinicthermoplastic resin may contain one or more crystalline propylenehomopolymers or copolymers of propylene having a melting temperaturegreater than 105° C. as measured by DSC. Preferred copolymers ofpropylene include, but are not limited to, terpolymers of propylene,impact copolymers of propylene, random polypropylene and mixturesthereof. Preferred comonomers may have 2 carbon atoms, or from 4 to 12carbon atoms. Preferably, the comonomer is ethylene. Such polyolefinicthermoplastic resin and methods for making the same are described inU.S. Pat. No. 6,342,565.

The term “random polypropylene” as used herein broadly means a copolymerof propylene having up to 9 wt. %, preferably 2 wt. % to 8 wt. % of analpha olefin comonomer. Preferred alpha olefin comonomers have 2 carbonatoms, or from 4 to 12 carbon atoms. Preferably, the alpha olefincomonomer is ethylene.

In one or more embodiments, the random polypropylene may have a 1%secant modulus of about 100 kPsi to about 200 kPsi, as measuredaccording to ASTM D790A. In one or more embodiments, the 1% secantmodulus can be 140 kPsi to 170 kPsi, as measured according to ASTMD790A. In one or more embodiments, the 1% secant modulus can be 140 kPsito 160 kPsi, as measured according to ASTM D790A. In one or moreembodiments, the 1% secant modulus can range from a low of about 100,110, or 125 kPsi to a high of about 145, 160, or 175 kPsi, as measuredaccording to ASTM D790A.

In one or more embodiments, the random polypropylene can have a densityof about 0.85 to about 0.95 g/cc, as measured by ASTM D792. In one ormore embodiments, the random polypropylene can have a density of about0.89 g/cc to 0.92 g/cc, as measured by ASTM D792. In one or moreembodiments, the density can range from a low of about 0.85, 0.87, or0.89 g/cc to a high of about 0.90, 0.91, 0.92 g/cc, as measured by ASTMD792.

Other polymers that may be included in the compositions of the inventioninclude isotactic poly(1-butene), such as PB0110M available from BasellPolyolefins.

Additive Oil

The polymer blends described herein can also optionally include one ormore additive oils. The term “additive oil” includes both “process oils”and “extender oils.” For example, “additive oil” may include hydrocarbonoils and plasticizers, such as organic esters and syntheticplasticizers. Many additive oils are derived from petroleum fractions,and have particular ASTM designations depending on whether they fallinto the class of paraffinic, naphthenic, or aromatic oils. Other typesof additive oils include mineral oil, alpha olefinic synthetic oils,such as liquid polybutylene, e.g., products sold under the trademarkParapol®. Additive oils other than petroleum based oils can also beused, such as oils derived from coal tar and pine tar, as well assynthetic oils, e.g., polyolefin materials (e.g., SpectraSyn™ Escorez™and Elevast™, all supplied by ExxonMobil Chemical Company).

The ordinarily skilled chemist will recognize which type of oil may beused with a particular composition, and will also be able to determinethe suitable amount (quantity) of oil to be added. The additive oil canbe present in amounts from about 5 to about 300 parts by weight per 100parts by weight of the blend.

In some embodiments, the additive oil comprises a polybutene oil.Preferable polybutene oils have an Mn of less than 15,000, and includehomopolymers or copolymers of olefin-derived units having from 3 to 8carbon atoms and more preferably from 4 to 6 carbon atoms. In one ormore embodiments, the polybutene is a homopolymer or copolymer of a C₄raffinate. An embodiment of preferred low molecular weight polymerstermed “polybutene” polymers is described in, for example, SYNTHETICLUBRICANTS AND HIGH-PERFORMANCE FUNCTIONAL FLUIDS, pp. 357-392 (LeslieR. Rudnick & Ronald L. Shubkin, ed., Marcel Dekker 1999) (hereinafter“polybutene processing oil” or “polybutene”).

In one or more embodiments, the polybutene processing oil is a copolymerhaving at least isobutylene derived units, and optionally 1-butenederived units, and/or 2-butene derived units. In one embodiment, thepolybutene is a homopolymer if isobutylene, or a copolymer ofisobutylene and 1-butene or 2-butene, or a terpolymer of isobutylene and1-butene and 2-butene, wherein the isobutylene derived units are from 40wt. % to 100 wt. % of the copolymer, the 1-butene derived units are from0 to 40 wt. % of the copolymer, and the 2-butene derived units are from0 to 40 wt. % of the copolymer. In another embodiment, the polybutene isa copolymer or terpolymer wherein the isobutylene derived units are from40 wt. % to 99 wt. % of the copolymer, the 1-butene derived units arefrom 2 wt. % to 40 wt. % of the copolymer, and the 2-butene derivedunits are from 0 to 30 wt. % of the copolymer. In yet anotherembodiment, the polybutene is a terpolymer of the three units, whereinthe isobutylene derived units are from 40 wt. % to 96 wt. % of thecopolymer, the 1-butene derived units are from 2 wt. % to 40 wt. % ofthe copolymer, and the 2-butene derived units are from 2 wt. % to 20 wt.% of the copolymer. In yet another embodiment, the polybutene is ahomopolymer or copolymer of isobutylene and 1-butene, wherein theisobutylene derived units are from 65 wt. % to 100 wt. % of thehomopolymer or copolymer, and the 1-butene derived units are from 0 to35 wt. % of the copolymer. Commercial examples of suitable processingoil include the PARAPOL™ series of processing oils or polybutene gradesor Indopol™ oils, from Soltex Synthetic Oils and Lubricants or fromBP/Innovene.

In certain embodiments, the processing oil or oils can be present atfrom 1 to 60, or from 2 to 40, or from 4 to 35, or from 5 to 30 parts byweight per 100 parts by weight of the blend.

Applications

The composition may be formed or shaped into a wide variety of finishedarticles by finishing methods well known to those of skill in the art.Such articles may include, but are not limited to, films, fibers, yarns,nonwovens, coatings, molded articles, and the like. Finished articlesmay be formed by any suitable process, such as for example extrusion,blow molding, injection molding, meltblowing, spunbonding, compressionmolding, fiber spinning, and other processes known to those familiarwith the art. The blends of the present invention are particularlyuseful in applications requiring stretchable elastic materials, such asin disposable diapers, training pants, incontinence pads, clothing,undergarments, sports apparel, automotive trim, weather-stripping,gaskets, and furniture upholstery, among others.

Crosslinking of Composition

The propylene-based polymer, including the polymer blend describedherein, of the present invention, whether compounded as described aboveor not and whether formed into finished articles or not, may be at leastpartially crosslinked by a variety of methods known in the art. One suchmethod for at least partially crosslinking the propylene-based polymer,including the polymer blend described herein or the composition is byexposing to energetic photons. In particular, crosslinking of thepropylene-based polymer, including the polymer blend described herein orthe composition may be accomplished by exposing to electromagneticradiation having a frequency greater than that of visible light, such asfor example near ultraviolet radiation, extreme ultraviolet radiation,soft x-rays, hard x-rays, gamma rays, and high-energy gamma rays. Incertain embodiments of the present invention, where the propylene-basedpolymer is substantially lack of diene-derived units, crosslinking isaccomplished by electron beam radiation.

Electron beam radiation is a form of ionizing energy that is generallyis characterized by its low penetration and high dose rates. Theelectrons are generated by equipment referred to as accelerators whichare capable of producing beams that are either pulsed or continuous. Theterm “beam” is meant to include any area exposed to electrons, which mayrange from a focused point to a broader area, such as a line or field.The electrons are produced by a series of cathodes (electrically heatedtungsten filaments) that generate a high concentration of electrons.These electrons are then accelerated across a potential. Theaccelerating potential is typically in the keV to MeV range (where eVdenotes electron volts), depending on the depth of penetration required.The irradiation dose is usually measured in Gray (unit) but also inrads, where 1Gy is equivalent to 100 rad, or, more typically, 10 kGyequals 1 Mrad. Commercial electron beam units generally range inenergies from 50 keV to greater than 10 MeV (million electron volts).

In one or more embodiments herein, the composition or articlescomprising the propylene-based polymer, including polymer blenddescribed herein, are at least partially crosslinked or cured so thatthey become heat-resistant. As used herein, the term “heat-resistant”refers to the ability of a polymer composition or an article formed froma polymer composition to pass the high temperature heat-setting testsdescribed herein. As used herein, the terms “cured,” “crosslinked,” “atleast partially cured,” and “at least partially crosslinked” refer to acomposition having at least 2 wt. % insolubles based on the total weightof the composition. In one or more embodiments, the compositionsdescribed herein can be cured to a degree so as to provide at least 3wt. %, or at least 5 wt. %, or at least 10 wt. %, or at least 20 wt. %,or at least 35 wt. %, or at least 45 wt. %, or at least 50 wt. %, or atleast 65 wt. %, or at least 75 wt. %, or at least 85 wt. %, or less than95 wt. % insolubles using xylene as the solvent by Soxhlet extraction.

In a particular embodiment, the crosslinking is accomplished bysubjecting the polymers described herein to electron beam radiation.Suitable electron beam equipment is available from E-BEAM Services,Inc., or from PCT Engineered Systems, LLC. In a particular embodiment,electrons are employed at a dose of about 200 kGy or less, or about 100kGy or less in multiple exposures. The source can be any electron beamunit operating in a range of about 50 KeV to greater than 10 MeV with apower output capable of supplying the desired dosage. The electronvoltage can be adjusted to appropriate levels, which may be, forexample, 100,000 eV; 300,000 eV; 1,000,000 eV; 2,000,000 eV; 3,000,000eV; or 6,000,000 eV. A wide range of apparatuses for irradiatingpolymers and polymeric articles is available.

Effective irradiation is generally carried out at a dosage from about 10kGy to about 200 kGy, or from about 10 kGy to about 100 kGy, or fromabout 20 to about 90 kGy, or from about 30 to about 80 kGy, or fromabout 40 kGy to about 60 kGy or from about 50 kGy to about 60 kGy. In aparticular aspect of this embodiment, the irradiation is carried out atroom temperature.

Without wishing to be bound by theory, it is believed that two competingprocesses occur upon irradiation of polymers comprising propylene andethylene, such as the inventive polymers described herein. In portionsof the polymer chains containing pendant methyl groups (such as thosepolymer units derived from propylene), the carbon atoms in the polymerbackbone are susceptible to chain scission upon irradiation, whichresults in lowered molecular weight. The irradiation process also breaksthe bonds between carbon and hydrogen atoms comprising the backbones ofthe polymer chains, creating free radicals that are available tocrosslink with free radicals on adjacent polymer chains. Thus,irradiation leads to crosslinking, which builds a polymer network, aswell as scission, which disrupts formation of a broad polymer network.To provide polymers with good tensile and elastic properties, it isdesired to reduce chain scission while encouraging crosslinking ofadjacent polymer chains.

In polymers containing predominantly propylene, the dominant mechanismwhich takes place upon irradiation is scissioning. In polyethylenepolymers, on the other hand, the dominant mechanism is crosslinking. Theinclusion of ethylene-derived units in the propylene-rich polymer blendsdescribed herein therefore enhances crosslinking and reduces chainscission, leading to improved crosslinking.

To further optimize the composition herein and enhance cross-linking,both a coagent and an antioxidant may be added to the polymer blendformulation in a compounding step prior to irradiation. Again, withoutwishing to be bound by theory, it is believed that coagents enhancecrosslinking behavior, while antioxidants suppress chain scission. Thesum total, therefore, is improved crosslinking when compared to polymershaving no coagent(s), antioxidant(s), or both. In other words, thepolymer chains of the inventive polymer blends described herein staylonger in length due to reduced scissioning, thus, forming a crosslinkednetwork that extends over a greater distance within the polymer blend.This enhanced crosslinking in turn leads to improved tension set,elongation, stress, and other mechanical properties of the polymers.

In another embodiment, crosslinking can be accomplished by exposure toone or more chemical agents in addition to the electron beam cure.Illustrative chemical agents include but are not limited to peroxidesand other free radical generating agents, sulfur compounds, phenolicresins, and silicon hydrides. In a particular aspect of this embodiment,the crosslinking agent is either a fluid or is converted to a fluid suchthat it can be applied uniformly to the article. Fluid crosslinkingagents include those compounds which are gases (e.g., sulfurdichloride), liquids (e.g., Trigonox C, available from Akzo Nobel),solutions (e.g., dicumyl peroxide in acetone), or suspensions thereof(e.g., a suspension or emulsion of dicumyl peroxide in water, or redoxsystems based on peroxides).

Illustrative peroxides include, but are not limited to dicumyl peroxide;di-tert-butyl peroxide; t-butyl perbenzoate; benzoyl peroxide; cumenehydroperoxide; t-butyl peroctoate; methyl ethyl ketone peroxide;2,5-dimethyl-2,5-di(t-butyl peroxy)hexane; lauryl peroxide; andtert-butyl peracetate. When used, peroxide curatives are generallyselected from organic peroxides. Examples of organic peroxides include,but are not limited to, di-tert-butyl peroxide; dicumyl peroxide;t-butylcumyl peroxide; α,α-bis(tert-butylperoxy) diisopropyl benzene;2,5-dimethyl 2,5-di(t-butylperoxy)hexane;1,1-di(t-butylperoxy)-3,3,5-trimethyl cyclohexane;butyl-4,4-bis(tert-butylperoxy) valerate; benzoyl peroxide; lauroylperoxide; dilauroyl peroxide; 2,5-dimethyl-2,5-di(tert-butylperoxy)hexene-3; and mixtures thereof. Also, diaryl peroxides; ketoneperoxides; peroxydicarbonates; peroxyesters; dialkyl peroxides;hydroperoxides; peroxyketals; and mixtures thereof may be used.

In one or more embodiments, the crosslinking can be carried out usinghydrosilylation techniques.

In one or more embodiments, the crosslinking can be carried out under aninert or oxygen-limited atmosphere. Suitable atmospheres can be providedby the use of helium, argon, nitrogen, carbon dioxide, xenon and/or avacuum.

Crosslinking either by chemical agents or by irradiation can be promotedwith a crosslinking catalyst, such as organic bases, carboxylic acids,and organometallic compounds including organic titanates and complexesor carboxylates of lead, cobalt, iron, nickel, zinc, and tin (such asdibutyltindilaurate, dioctyltinmaleate, dibutyltindiacetate,dibutyltindioctoate, stannous acetate, stannous octoate, leadnaphthenate, zinc caprylate, cobalt naphthenate, and the like). In thecase where irradiation is accomplished via ultraviolet radiation, one ormore UV sensitizers, which generate free radicals in the presence of UVradiation, may be employed to promote crosslinking. Such UV sensitizersare known in the art, and include halogenated polynuclear ketones,organic carbonyl compounds selected from alkyl phenones, isbenzophenones, and tricyclic fused ring compounds, and carbonylatedphenol nuclear sulfonyl chlorides.

Suitable UV sensitizers may be selected from those organic chemicalcompounds conventionally employed to promote UV-initiated formation ofradicals either by intramolecular homolytic bond cleavage or byintermolecular hydrogen abstraction. Such agents include organiccompounds having aryl carbonyl or tertiary amino groups. Among thecompounds suitable for use are benzophenone; acetophenone; benzil;benzaldehyde; o-chlorobenzaldehyde; xanthone; thioxanthone;9,10-anthraquinone; 1-hydroxycyclohexyl phenyl ketone;2,2-diethoxyacetophenone; dimethoxyphenylacetophenone; methyldiethanolamine; dimethylaminobenzoate;2-hydroxy-2-methyl-1-phenylpropane-1-one; 2,2-di-sec-butoxyacetophenone;2,2-dimethoxy-1,2-diphenylethan-1-one; benzil dimethoxyketal; benzoinmethyl ether; and phenyl glyoxal. Upon exposure to UV radiation, avariety of photochemical transformations may occur, for example, the UVinitiator may form free radical reactive fragments that react with theacrylate end groups of the multifunctional acrylic or methacryliccrosslinking agent. This initiates crosslinking of the polymer as wellas homopolymerization of the acrylic or methacrylic crosslinking agent.

In one embodiment, the UV sensitizer includes at least one of abenzophenone photoinitiator; a phenylglyoxylate photoinitiator; an alphahydroxy ketone photoinitiator; a combination of acyl phosphine oxide andan alpha hydroxy ketone photoinitiator;2,2-aimethoxy-1,2-diphenylethan-1-one; and a combination ofoxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester andoxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester. Commerciallyavailable photoinitiators include Darocur BP, Darocur MBF, Irgacur 651,and Irgacure 754, available from Ciba Geigy, now BASF Chemical Company.

In one or more embodiments, the composition contains at least 0.1 wt. %of a UV sensitizer, based on the total weight of the composition. In oneor more embodiments, the amount of UV sensitizer(s) can range from about0.1 wt. % to about 10 wt. %, based on the total weight of thecomposition. In one or more embodiments, the amount of UV sensitizers(s)can range from a low of about 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.5 wt.%, or 1 wt. %, to a high of about 2.5 wt. %, 3 wt. %, 5 wt. %, or 8 wt.%, based on the total weight of the composition. In one or moreembodiments, the amount of UV sensitizers(s) is about 1 wt. % to about 3wt. %, based on the total weight of the composition. In one or moreembodiments, the amount of UV sensitizers(s) is about 1 wt. %, 1.5 wt.%, or 2 wt. %, based on the total weight of the composition.

The wavelength spectrum of UV radiation used to effect the curingreaction typically corresponds to the absorption maximum of the UVinitiator. The wavelength can be from about 10 nm to about 400 nm.Preferably, the wavelength is from about 100 to about 400 nm, preferablyabout 200 to about 350 nm. Suitable UV radiation sources include mediumpressure mercury vapor lamps, electrodeless lamps, pulsed xenon lamps,and hybrid xenon/mercury vapor lamps. An exemplary arrangement comprisesone or more lamps together with a reflector, which diffuses theradiation evenly over the surface to be irradiated. Suitable UVradiation equipment includes those available from Fusion UV System Inc.,such as the F300-6 curing chamber.

EXAMPLES

The foregoing discussion can be further described with reference to thefollowing non-limiting examples. Compositions containing at least onepropylene-based copolymer in accordance with one or more embodimentsdescribed were prepared.

Table 1 summarizes the formulations of the compositions. The materialsused the invention are as follows.

VM6102 is a polymer blend having 16 wt. % of ethylene and nodiene-derived units and is commercially available from ExxonMobilChemical Company under the tradename Vistamaxx™ 6102 propylene-basedpolymer.

VM6100 is a metallocene-catalyzed propylene/ethylene copolymer having 16wt. % of ethylene and no diene-derived units and is commerciallyavailable from ExxonMobil Chemical Company under the tradenameVistamaxx™ 6100 propylene-based polymer.

Exact 5101 is an ethylene-octene copolymer and is commercially availablefrom ExxonMobil Chemical Company.

TAC is a triallylcyanurate commercially available from Sartomer Companyunder the trade name Sartomer 507.

PLB 6941 is a master batch of TAC commercially available from FloPolymers.

PP 5341 is a 0.8 MFR (230° C., 2.16 kg) isotactic polypropylene (iPP)that is commercially available from ExxonMobil Chemical Company.

RCP 9122 is a random copolymer containing 2-3 wt. % of ethylene derivedunits, the balance is propylene. The RCP 9122 has a MFR (2.16 kg at 230°C.) of 2.1 g/10 min and a density of 0.9 g/cm³. The 1% secant flexuralmodulus is 140 kPsi, as measured by ASTM D790A. RCP 9122 is commerciallyavailable from ExxonMobil Chemical Company.

Sartomer 350 is a trimethylolpropane trimethacrylate co-agent that iscommercially available from Sartomer Company, Inc. located in Exton, Pa.

Irgafos 168 is an antioxidant commercially available from Ciba SpecialtyChemicals.

MDV 91-9 is an EP copolymer (ExxonMobil Chemical) with about 60 wt. %ethylene and has a Mooney viscosity (ML (1+4) at 125° C.) about 19 andnarrow molecular weight distribution.

TABLE 1 Formulations Material, phr (parts by Comparative ExamplesExamples weight) 1 2 3 4 5 1 2 3 VM6100 100 90 79 PP 5341 10 5 5 5 Exact5101 14 Exxon RCP 9122 5 5 5 TAC (triallyl 5 cyanurate) PLB 6941 (TAC) 2Sartomer 350 3 3 Irgastab FS 410 Irgafos 168 0.2 0.2 0.2 MDV 91-9 10 VM6102 95 95 89.8 91.8 81.8 Total PHR 100.00 100.00 100.00 100 100 100.00100.00 100.00

VM6102 propylene-based polymers were compounded with a polypropylene, acoagent, an antioxidant, or combinations thereof. Each composition wasprepared in a Brabender thermoplastic compounder. The pellets of blendsof the propylene-based polymers with thermoplastic components werecharged into the Brabender in the presence of a nitrogen blanket alongwith the antioxidants at a melt temperature of 150° C. for 3 minutes.The temperature was then lowered to 140° C. and the coagent,antioxidant, and/or polypropylene were added and mixed for about 2minutes to obtain a homogenous blend. The compounded blends were thenmolded into plaques having a thickness of 75 mils and films having athickness of 10 mils on a compression molding press.

The resulting compounded formulations, identified herein as Examples 1to 3, were crosslinked using electron beam radiation, first at 50 kGyand then at 60 kGy. The mechanical properties of Examples 1-3 arereported in Table 2 below.

Comparative examples 1-5 were also prepared from the propylene-basedpolymer is VM 6102 and VM 6100 by the same procedure, except that theblends do not contain a coagent and an antioxidant. The mechanicalproperties of Comparative Examples 1-5 are reported in Table 2 below.

Physical properties of the compositions were evaluated before and aftercuring. Hardness was tested according to ASTM 2240, and the tension setof the blends was tested according to ASTM D412 at room temperature and70° C. For room temperature and 70° C. testing for tension set, thesample was aged at the test temperature for 30 minutes under 50% tensionon Jig and annealed at room temperature for 30 minutes after removingfrom the Jig. A xylene Soxhlet solvent extraction test was conductedaccording to ASTM D5492 on the cured samples using a Soxhlet extractor(extraction time=12 hrs) to understand the level of crosslinked materialafter electron beam curing. Results are expressed as: percent xyleneinsoluble=weight after extraction/weight before extraction*100.

TABLE 2 Properties of blends before and after electron beamcrosslinking. TESTED Comparative Examples Examples PROPERTIES 1 2 3 4 51 2 3 Before Electron-beaming Hardness, Shore A, 15 s. 59 66 69 57 5553.8 59 60 Stress at Break, MPa 10.2 12.7 13.6 9.7 10.7 13.0 11.6Elongation at break, (%) 791 774 778 1013 1012 did not 861 838 breakPeak stress, (MPa) N/A N/A N/A N/A N/A 9.0 13.1 11.9 Peak Elongation,(%) N/A N/A N/A N/A N/A 840 840 820 100% Mod. (MPa) 1.9 2.4 2.6 1.6 1.61.61 2.0 1.9 Tension Set (%), 23° C. 4 5 5 N/A N/A 8 N/A N/A Tension Set(%), 70° C. Broke 49 50 N/A N/A 46 N/A N/A MFR (230 C., 2.16 kg) 4.3 3.33.7 3.1 3.2 4.4 3.5 3.1 Electron-beamed at 50 kGy Hardness, Shore A, 15s. 59 65 66 NA NA NA NA NA Stress at Break, MPa 6.0 9.2 9.7 5.5 7.0 8.214.3 12.1 Elongation at break, (%) 791 787 787 1834 2004 954 789 818Peak stress, (MPa) N/A N/A N/A N/A N/A N/A 14.6 12.7 Peak Elongation,(%) N/A N/A N/A N/A N/A N/A 740 800 100% Mod. (MPa) 1.7 2.3 2.4 1.5 1.61.6 2.7 2.4 Tension Set (%), 23° C. 4 5 4 NA NA 5 4.0 5.0 Tension Set(%), 70° C. 42 40 37 NA NA 40 32.5 33.0 Xylene Extraction, % insoluble 00 27 N/A N/A 32 74 59 Electron-beamed at 60 kGy Stress at Break, MPa N/AN/A N/A 5.7 6.0 N/A 15.4 11.9 Elongation at break, (%) N/A N/A N/A 19492190 N/A 805 807 Peak stress, (MPa) N/A N/A N/A N/A N/A N/A 15.6 12.6Peak Elongation, (%) N/A N/A N/A N/A N/A N/A 700 780 100% Mod. (MPa) N/AN/A N/A 1.4 1.4 N/A 2.7 2.5 Tension Set (%), 23° C. N/A N/A N/A N/A N/AN/A 5.0 4.0 Tension Set (%), 70° C. N/A N/A N/A N/A N/A N/A 32.0 N/AXylene Extraction, % insoluble N/A N/A N/A N/A N/A N/A 75 75

As is evident from a comparison of the mechanical properties of Examples1-3 with those of Comparative Examples 1-5, the addition of at least onecoagent and at least one antioxidant to the polymer blends of theinvention results in greatly improved mechanical properties. Forexample, a comparison of the difference in peak stress before and afterelectron-beaming for all of the examples shows that the peak stressmeasurements increase (i.e., improve) for Examples 1-3, which contain acoagent and an antioxidant, while the peak stress measurements forComparative Examples 1-5 decrease (i.e., worsen) upon crosslinking. Asimilar comparison of tension set values at 70° C. for all examplesshows that, while an improvement in tension set (indicated by a decreasein the tension set %) is exhibited by all of the samples, theimprovement is much greater for those samples containing both a coagentand an antioxidant. The results shows that the crosslinking by electronbeam of those compositions containing both a coagent and an antioxidantare effective even though the propylene-based polymer substantiallylacking diene-derived units.

FIGS. 1 and 2 illustrate the improved tensile properties and hysteresisproperties which result from the crosslinking of the composition. Inparticular, FIG. 1 shows the improvement of Tension Set at 70° C. of thecomposition of Example 2 after 50 kGy electron beam radiation. FIG. 2shows the improvement of Tension Set at 70° C. of the composition ofExample 3 after 50 kGy electron beam radiation.

Fiber properties of selected blends were also evaluated. Blends ofExamples 2 and 3 were selected based on their excellent balance ofphysical properties. To test the physical properties of the fibers, theselected blends were spun into fiber using a partially oriented yarnline having a L:D ratio of 24:1. The spinnerette had 72 holes. Each holehad a diameter of 0.6 mm. The output of the line ranged from about 0.4to 2 gram/hole/min, with a Godet speed close to 5,000 m/min and awinding speed of from 100 m/min to 3,000 m/min. The extruded fibers werecooled by quenched air having a temperature of about 45° F. to 55° F.

Table 3 summarizes the physical properties of both the cured and uncuredfibers. As shown below, the cured fibers exhibited excellentspinnability and fiber formation.

TABLE 3 Properties of fibers Electron Winding beam Xylene Blend speed,dosage, Count, den (72 Tenacity, Elongation, insoluble, TS,% at TS,% at(Run#) m/min KGy filaments) g/den % % 23° C. 70° C. 2(#1) 260 0 16090.49 161 n/a 5.5 22 2(#2) 260 40 1609 0.41 124 24 2.5 24 2(#3) 260 01625 0.51 158 n/a 1 14 2(#4) 260 50 1629 0.36 109 30 5 21 2(#5) 260 01542 0.4 122 n/a 1.5 17.5 2(#6) 260 60 1536 0.42 128 27 4 17.5 2(#7) 2600 1609 0.41 127 n/a 2 17 2(#8) 260 100 1643 0.35 137 33 1 20 3(#9) 145 02923 0.26 130 n/a 2 29 3(#10) 145 40 2863 0.29 166 24 1 21 3(#11) 145 02919 0.31 193 n/a 0.5 20 3(#12) 145 50 2866 0.27 177 30 0.5 22 3(#13)145 0 2968 0.28 143 n/a 1 30 3(#14) 145 60 2868 0.3 209 30 2 25 3(#15)145 0 2998 0.27 153 n/a 0.5 20 3(#16) 145 100 2901 0.25 165 40 0.5 20

Monolayer films from blends 2 and 3 were also prepared. The films weremade by compression molding, similar to the process used for making theplaques. The thickness of each film was about 10 mil.

The results are shown below in Table 4, including the physicalproperties of the films before electron beam cure and after electronbeam cure using a dosage of 50 kGy.

TABLE 4 Properties of Films Blend PROPERTIES 2 3 Before Electron beamingStress at Break, psi 2508 2345 Elongation at break, (%) 1868 1790 100%Mod. (psi) 305 299 Energy at Break, in * lbf 31.3 27.4 After Electronbeamed at 50 kGy Stress at Break, psi 2368 2383 Elongation at break, (%)1591 1767 100% Mod., psi 349 337 Energy at Break, in * lbf 24.6 28.1Xylene Extraction, % insolubles 41 44

It was surprisingly found that the electron beam cured films maintainedtheir tensile strength after curing even at such high levels ofcrosslinking as measured by the xylene extraction, percent insolubles.The opposite would have been expected considering the strengthproperties of cured films are usually sacrificed during crosslinking.

For purposes of convenience, various specific test procedures areidentified above for determining certain properties such as tension set,percent elongation at break, Shore A Hardness, etc. However, when aperson of ordinary skill reads this patent and wishes to is determinewhether a composition or polymer has a particular property identified ina claim, then any published or well-recognized method or test procedurecan be followed to determine that property, although the specificallyidentified procedure is preferred. Each claim should be construed tocover the results of any of such procedures, even to the extentdifferent procedures can yield different results or measurements. Thus,a person of ordinary skill in the art is to expect experimentalvariations in measured properties that are reflected in the claims. Allnumerical values can be considered to be “about” or “approximately” thestated value, in view of the nature of testing in general.

Having described the various aspects of the compositions herein, furtherspecific embodiments of the invention include those set forth in thefollowing lettered paragraphs:

-   AA. A method for making a crosslinked composition comprising the    step of crosslinking the composition using electron beam radiation    having an electron beam dose of about 200 kGy or less, the    composition comprising:    -   i) a propylene-based polymer comprising from about 75 wt. % to        about 99 wt. % propylene-derived units, from about 1 wt. % to        about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.1 wt. % diene-derived units, based on the weight        of the propylene-based polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate; and    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine-   AB. The method of Paragraph AA, wherein the electron beam dose is    about 100 kGy.-   AC. The method of Paragraphs AA or AB, wherein the electron beam    dose is of from about 40 kGy to about 60 kGy.-   AD. The method of any of Paragraphs AA-AC, wherein the    propylene-based polymer comprises less than 0.05 wt. % diene-derived    units based on the weight of the propylene-based polymer.-   AE. The method of any of Paragraphs AA-AD, wherein the    propylene-based polymer comprises less than 0.01 wt. % diene-derived    units based on the weight of the propylene-based polymer.-   AF. The method of any of Paragraphs AA-AE, wherein the    propylene-based polymer comprises 0 wt. % diene-derived units based    on the weight of the propylene-based polymer.-   AG. The method of any of Paragraphs AA-AF, wherein the    propylene-based polymer comprises from about 1 wt. % to about 25 wt.    % units derived from ethylene, butene, hexene, and/or octane based    on the weight of the propylene-based polymer.-   AH. The method of any of Paragraphs AA-AG, wherein the    propylene-based polymer comprises from about 5 wt. % to about 25 wt.    % of units derived from ethylene and/or butene based on the weight    of the propylene-based polymer.-   AI. The method of any of Paragraphs AA-AH, wherein the    propylene-based polymer comprises from about 5 wt. % to about 25 wt.    % of units derived from ethylene and/or hexene based on the weight    of the propylene-based polymer.-   AJ. The method of any of Paragraphs AA-AI, wherein the    propylene-based polymer has a heat of fusion from about 0.5 J/g to    about 80 J/g.-   AK. The method of any of Paragraphs AA-AJ, wherein the    propylene-based polymer has a triad tacticity of three propylene    units, as determined by ¹³C NMR, of 75% or greater.-   AL. The method of any of Paragraphs AA-AK, wherein the    propylene-based polymer is a polymer blend formed by forming a    reactor blend of a first polymer formed in a first reactor and a    second polymer formed in a second reactor, the first polymer    comprising from about 75 wt. % to about 99 wt. % propylene-derived    units, from about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀    α-olefin-derived units, and less than 0.1 wt. % diene-derived units,    based on the weight of the first polymer; and the second polymer    comprising from about 75 wt. % to about 99 wt. % propylene-derived    units, from about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀    α-olefin-derived units, and less than 0.1 wt. % diene-derived units,    based on the weight of the second polymer.-   AM. The method of Paragraph AL, wherein the first polymer comprises    from about 12 wt. % to about 20 wt. % ethylene-derived units based    on the weight of the first polymer.-   AN. The method of Paragraphs AL or AM, wherein the second polymer    comprises from about 3 wt. % to about 10 wt. % ethylene-derived    units based on the weight of the second polymer.-   AO. The method of any of Paragraphs AL-AN, wherein the polymer blend    comprises from about 10 wt. % to about 18 wt. % ethylene-derived    units based on the weight of the polymer blend.-   AP. The method of any of Paragraphs AA-AO, wherein the at least one    of multifunctional acrylate, multifunctional methacrylate,    functionalized polybutadiene resin, functionalized cyanurate, and    allyl isocyanurate is present in an amount of from about 0.1 wt. %    to 15 wt. % based on the weight of the composition.-   AQ. The method of any of Paragraphs AA-AP, wherein the at least one    of hindered phenol, phosphite, and hindered amine is present in an    amount of from about 0.1 wt. % to 5 wt. % based on the weight of the    composition.-   AR. The method of any of Paragraphs AA-AQ, wherein the composition    further comprises at least one of a secondary elastomer and    polyolefinic thermoplastic resin.-   AS. The method of any of Paragraphs AA-AR, wherein the polyolefinic    thermoplastic resin comprises at least one of an isotactic    polypropylene, random copolymer, and impact copolymer.-   AT. An article comprising the crosslinked composition made by the    method of Paragraphs AA-AS.-   AU. The article of Paragraph AV comprising film or nonwoven fiber.-   AV. A composition comprising:    -   i) a polymer blend formed by forming a reactor blend of a first        polymer formed in a first reactor and a second polymer formed in        a second reactor, the first polymer comprising from about 75 wt.        % to about 99 wt. % propylene-derived units, from about 1 wt. %        to about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.05 wt. % diene-derived units based on the weight        of the first polymer; and the second polymer comprising from        about 75 wt. % to about 99 wt. % propylene-derived units, from        about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀        α-olefin-derived units, and less than 0.05 wt. % diene-derived        units based on the weight of the second polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate; and    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine-   AW. The composition of Paragraph AV, wherein the polymer blend    comprises 0 wt. % diene-derived units based on the weight of the    polymer blend.-   AX. The composition of Paragraph AV being subjected to electron beam    radiation having an electron beam dose of about 200 kGy or less.-   AY. The composition of Paragraph AV being subjected to electron beam    radiation having an electron beam dose of about 40 kGy to about 60    kGy.-   AZ. The composition of Paragraphs AX or AY having greater than 40%    xylene insolubles as measured according to ASTM-D 5492.-   BA. A crosslinked composition, comprising:    -   i) a propylene-based polymer comprising from about 75 wt. % to        about 99 wt. % propylene-derived units, from about 1 wt. % to        about 25 wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units,        and less than 0.1 wt. % diene-derived units, based on the weight        of the propylene-based polymer;    -   ii) at least one of a multifunctional acrylate, multifunctional        methacrylate, functionalized polybutadiene resin, functionalized        cyanurate, and allyl isocyanurate;    -   iii) at least one of a hindered phenol, phosphite, and hindered        amine; and    -   iv) a polyolefinic thermoplastic resin,

wherein the crosslinked composition has greater than 40% xyleneinsolubles as measured according to ASTM-D 5492.

-   BB. The crosslinked composition of Paragraph BA, wherein the    propylene-based polymer comprising 0 wt. % diene-derived units based    on the weight of the propylene-based polymer.-   BC. The crosslinked composition of Paragraphs BA or BB, wherein the    multifunctional methacrylate comprises trimethylolpropane    trimethacrylate.-   BD. An article comprising the crosslinked composition of any of    Paragraphs BA-BC.-   BE. The article of Paragraph BD comprising film or nonwoven fiber.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges from any lower limit to any upper limit arecontemplated unless otherwise indicated. Certain lower limits, upperlimits and ranges appear in one or more claims below. All numericalvalues are “about” or “approximately” the indicated value, and take intoaccount experimental error and variations that would be expected by aperson having ordinary skill in the art.

To the extent a term used in a claim is not defined above, it should begiven the broadest definition persons in the pertinent art have giventhat term as reflected in at least one printed publication or issuedpatent. Furthermore, all patents, test procedures, and other documentscited in this application are fully incorporated by reference to theextent such disclosure is not inconsistent with this application and forall jurisdictions in which such incorporation is permitted.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

Each of the appended claims defines a separate invention, which forinfringement purposes is recognized as including equivalents of thevarious elements or limitations specified in the claims. Depending onthe context, all references herein to the “invention” may in some casesrefer to certain specific embodiments only. In other cases it will berecognized that references to the “invention” will refer to subjectmatter recited in one or more, but not necessarily all, of the claims.Each of the inventions is described herein, including specificembodiments, versions and examples, but the inventions are not limitedto these embodiments, versions or examples, which are included to enablea person having ordinary skill in the art to make and use theinventions, when the information in this patent is combined withavailable information and technology.

1. A method for making a crosslinked composition comprising the step ofcrosslinking the composition using electron beam radiation having anelectron beam dose of about 200 kGy or less, the composition comprising:i) a propylene-based polymer comprising from about 75 wt. % to about 99wt. % propylene-derived units, from about 1 wt. % to about 25 wt. %ethylene and/or C₄-C₂₀ α-olefin-derived units, and less than 0.1 wt. %diene-derived units, based on the weight of the propylene-based polymer;ii) at least one of a multifunctional acrylate, multifunctionalmethacrylate, functionalized polybutadiene resin, functionalizedcyanurate, and allyl isocyanurate; and iii) at least one of a hinderedphenol, phosphite, and hindered amine.
 2. The method of claim 1, whereinthe electron beam dose is about 100 kGy or less.
 3. The method of claim1, wherein the electron beam dose is of from about 40 kGy to about 60kGy.
 4. The method of claim 1, wherein the propylene-based polymercomprises less than 0.01 wt. % diene-derived units based on the weightof the propylene-based polymer.
 5. The method of claim 1, wherein thepropylene-based polymer comprises 0 wt. % diene-derived units based onthe weight of the propylene-based polymer.
 6. The method of claim 1,wherein the propylene-based polymer comprises from about 5 wt. % toabout 25 wt. % units derived from ethylene, butene, hexene, and/oroctane based on the weight of the propylene-based polymer.
 7. The methodof claim 1, wherein the propylene-based polymer has a heat of fusionfrom about 0.5 J/g to about 80 J/g.
 8. The method of claim 1, whereinthe propylene-based polymer has a triad tacticity of three propyleneunits, as determined by ¹³C NMR, of 75% or greater.
 9. The method ofclaim 1, wherein the propylene-based polymer is a polymer blend formedby forming a reactor blend of a first polymer formed in a first reactorand a second polymer formed in a second reactor, the first polymercomprising from about 75 wt. % to about 99 wt. % propylene-derivedunits, from about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀α-olefin-derived units, and less than 0.1 wt. % diene-derived units,based on the weight of the first polymer; and the second polymercomprising from about 75 wt. % to about 99 wt. % propylene-derivedunits, from about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀α-olefin-derived units, and less than 0.1 wt. % diene-derived units,based on the weight of the second polymer.
 10. The method of claim 9,wherein the first polymer comprises from about 12 wt. % to about 20 wt.% ethylene-derived units based on the weight of the first polymer. 11.The method of claim 9, wherein the second polymer comprises from about 3wt. % to about 10 wt. % ethylene-derived units based on the weight ofthe second polymer.
 12. The method of claim 9, wherein the polymer blendcomprises from about 10 wt. % to about 18 wt. % ethylene-derived unitsbased on the weight of the polymer blend.
 13. The method of claim 1,wherein the at least one of multifunctional acrylate, multifunctionalmethacrylate, functionalized polybutadiene resin, functionalizedcyanurate, and allyl isocyanurate is present in an amount of from about0.1 wt. % to 15 wt. % based on the weight of the composition.
 14. Themethod of claim 1, wherein the at least one of hindered phenol,phosphite, and hindered amine is present in an amount of from about 0.1wt. % to 5 wt. % based on the weight of the composition.
 15. The methodof claim 1, wherein the composition further comprises at least one of asecondary elastomer and a polyolefinic thermoplastic resin.
 16. Themethod of claim 15, wherein the polyolefinic thermoplastic resincomprises at least one of an isotactic polypropylene, a randomcopolymer, and an impact copolymer.
 17. An article comprising acrosslinked composition made by the method of claim
 1. 18. The articleof claim 17 comprising film or nonwoven fiber.
 19. A compositioncomprising: i) a polymer blend formed by forming a reactor blend of afirst polymer formed in a first reactor and a second polymer formed in asecond reactor, the first polymer comprising from about 75 wt. % toabout 99 wt. % propylene-derived units, from about 1 wt. % to about 25wt. % ethylene and/or C₄-C₂₀ α-olefin-derived units, and less than 0.05wt. % diene-derived units based on the weight of the first polymer; andthe second polymer comprising from about 75 wt. % to about 99 wt. %propylene-derived units, from about 1 wt. % to about 25 wt. % ethyleneand/or C₄-C₂₀ α-olefin-derived units, and less than 0.05 wt. %diene-derived units based on the weight of the second polymer; ii) atleast one of a multifunctional acrylate, multifunctional methacrylate,functionalized polybutadiene resin, functionalized cyanurate, and allylisocyanurate; and iii) at least one of a hindered phenol, phosphite, andhindered amine.
 20. The composition of claim 19, wherein the polymerblend comprises 0 wt. % diene-derived units based on the weight of thepolymer blend.
 21. The composition of claim 19, wherein the compositionis subjected to electron beam radiation having an electron beam dose ofabout 100 kGy or less.
 22. The composition of claim 21 having greaterthan 40% xylene insolubles as measured according to ASTM-D
 5492. 23. Acrosslinked composition, comprising: i) a propylene-based polymercomprising from about 75 wt. % to about 99 wt. % propylene-derivedunits, from about 1 wt. % to about 25 wt. % ethylene and/or C₄-C₂₀α-olefin-derived units, and less than 0.1 wt. % diene-derived units,based on the weight of the propylene-based polymer; ii) at least one ofa multifunctional acrylate, multifunctional methacrylate, functionalizedpolybutadiene resin, functionalized cyanurate, and allyl isocyanurate;iii) at least one of a hindered phenol, phosphite, and hindered amine;and iv) a polyolefinic thermoplastic resin, wherein the crosslinkedcomposition has greater than 40% xylene insolubles as measured accordingto ASTM-D
 5492. 24. The crosslinked composition of claim 23, wherein thepropylene-based polymer comprises 0 wt. % diene-derived units based onthe weight of the propylene-based polymer.
 25. An article comprising thecrosslinked composition of claim 23.